sq-23377 and Inflammation

Topics: Allergens; Asthma; Bronchial Provocation Tests; Bronchoalveolar Lavage Fluid; Cells, Cultured; Chemotaxis, Leukocyte; Clone Cells; Flow Cytometry; Gene Expression Regulation; Gene Rearrangement, T-Lymphocyte; Humans; Hypersensitivity; Hypersensitivity, Immediate; Inflammation; Interferon-gamma; Interleukins; Ionomycin; Lymphocyte Activation; Phytohemagglutinins; Receptors, Antigen, T-Cell, alpha-beta; Staining and Labeling; T-Lymphocyte Subsets; Tetradecanoylphorbol Acetate

Prior exposure of granulocytes to inflammatory mediators such as chemotactic factors, colony-stimulating factors and tumor necrosis factor primes the cells for enhanced activity of the respiratory burst, which appears not only to play an essential role in the increased host-defenses against invading microorganisms but also to be responsible for tissue damage at the inflammatory sites. The molecular basis for this priming is presently under investigation. Changes in one or more of the signal transduction events may lead to more efficient stimulation of the NADPH oxidase responsible for the respiratory burst. The mechanisms of priming appear to be different according to the priming stimuli: the chemotactic peptide and the Ca2+ ionophore may prime the cells by causing an increase in cytoplasmic free Ca2+; phorbol esters by activating protein kinase C; and colony-stimulating factors and tumor necrosis factor by activating the distinct mechanism, which is independent of an increase in cytoplasmic free Ca2+ and activation of protein kinase C.

Topics: Animals; Calcium; Colony-Stimulating Factors; Granulocytes; Humans; In Vitro Techniques; Inflammation; Ionomycin; Membrane Potentials; N-Formylmethionine Leucyl-Phenylalanine; Oxygen; Tetradecanoylphorbol Acetate; Tumor Necrosis Factor-alpha

The excessive amount of reactive species under chronic inflammation, which are accompanied by an increase body temperature, lead to diabetic complications. Phagocyte NADPH oxidase is the key enzyme in these processes. The role of high temperature in its regulation in diabetes is not clear. The aim was to investigate the effect of high temperature on NADPH-oxidase-dependent generation of reactive species in diabetic patients. Chemiluminescent method was applied to assess respiratory burst kinetics initiated by opsonized zymosan in blood or phorbol ester in isolated granulocytes. Analyzing ROC curves, the main predictors and changes in stages of activation of NADPH oxidase were determined. Phosphoisoforms of p47

Topics: Diabetes Mellitus, Type 2; Humans; Inflammation; Ionomycin; NADP; NADPH Oxidases; Neutrophils; Phorbol Esters; Phosphoproteins; Temperature; Zymosan

Interleukin-5 (IL-5) strongly initiates the asthmatic inflammatory response, which affects 300 million patients with asthma annually worldwide, through oxidative stress generation. Citrus flavonoids have beneficial properties, such as anti-inflammatory and antioxidant properties, but the precise molecular mechanism of the inhibition of the asthmatic inflammatory response is still unclear. This study aimed to investigate the underlying mechanisms of ROS and IL-5 reduction with citrus flavonoid treatment in PMA/ionomycin-induced EL-4 cells. Our results showed that hesperetin and gardenin A dramatically suppressed ROS and IL-5 production through distinct pathways. Interestingly, hesperidin induced HO-1 expression through the transcription factor Nrf2 coupled with the PI3K/AKT or ERK/JNK signaling pathway, consequently downregulating NFAT activity and IL-5 secretion. Likewise, gardenin A induced HO-1 expression and subsequently suppressed IL-5 production by reducing NFAT activity and upregulating PPARγ in EL-4 cells, suggesting that inducing HO-1 expression may inhibit asthmatic inflammation. Altogether, hesperidin and gardenin A have great potential for regulating the asthma-associated immune responses through antioxidant properties.

Topics: Animals; Asthma; Cell Line, Tumor; Citrus; Flavonoids; Inflammation; Interleukin-5; Ionomycin; Mice; Reactive Oxygen Species

Restoration of kidney tubular epithelium following sublethal injury sequentially involves partial epithelial-mesenchymal transition (pEMT), proliferation, and further redifferentiation into specialized tubule epithelial cells (TECs). Because the immunosuppressant cyclosporine-A produces pEMT in TECs and inhibits the peptidyl-prolyl isomerase (PPIase) activity of cyclophilin (Cyp) proteins, we hypothesized that cyclophilins could regulate TEC phenotype. Here we demonstrate that in cultured TECs, CypA silencing triggers loss of epithelial features and enhances transforming growth factor β (TGFβ)-induced EMT in association with upregulation of epithelial repressors Slug and Snail. This pro-epithelial action of CypA relies on its PPIase activity. By contrast, CypB emerges as an epithelial repressor, because CypB silencing promotes epithelial differentiation, prevents TGFβ-induced EMT, and induces tubular structures in 3D cultures. In addition, in the kidneys of CypB knockout mice subjected to unilateral ureteral obstruction, inflammatory and pro-fibrotic events were attenuated. CypB silencing/knockout leads to Slug, but not Snail, downregulation. CypB support of Slug expression depends on its endoplasmic reticulum location, where it interacts with calreticulin, a calcium-buffering chaperone related to Slug expression. As CypB silencing reduces ionomycin-induced calcium release and Slug upregulation, we suggest that Slug expression may rely on CypB modulation of calreticulin-dependent calcium signaling. In conclusion, this work uncovers new roles for CypA and CypB in modulating TEC plasticity and identifies CypB as a druggable target potentially relevant in promoting kidney repair.

Topics: Animals; Basigin; Calcium; Cell Line; Cyclophilins; Endoplasmic Reticulum; Epithelial Cells; Fibrosis; Gene Silencing; Humans; Inflammation; Ionomycin; Kidney Tubules; Mice; Phenotype; Protein Transport; Smad Proteins; Snail Family Transcription Factors; Thapsigargin; Transforming Growth Factor beta; Ureteral Obstruction

Cross-sectional studies have shown that exposure to indoor moisture damage and mold may be associated with subclinical inflammation. Our aim was to determine whether early age exposure to moisture damage or mold is prospectively associated with subclinical systemic inflammation or with immune responsiveness in later childhood. Home inspections were performed in children's homes in the first year of life. At age 6 years, subclinical systemic inflammation was measured by serum C-reactive protein (CRP) and blood leukocytes and immune responsiveness by ex vivo production of interleukin 1-beta (IL-1β), IL-6, and tumor necrosis factor alpha (TNF-α) in whole blood cultures without stimulation or after 24 hours stimulation with phorbol 12-myristate 13-acetate and ionomycin (PI), lipopolysaccharide (LPS), or peptidoglycan (PPG) in 251-270 children. Moisture damage in child's main living areas in infancy was not significantly associated with elevated levels of CRP or leukocytes at 6 years. In contrast, there was some suggestion for an effect on immune responsiveness, as moisture damage with visible mold was positively associated with LPS-stimulated production of TNF-α and minor moisture damage was inversely associated with PI-stimulated IL-1β. While early life exposure to mold damage may have some influence on later immune responsiveness, it does not seem to increase subclinical systemic inflammation in later life.

Topics: Air Pollutants; Air Pollution, Indoor; C-Reactive Protein; Child; Cytokines; Environmental Exposure; Female; Fungi; Humans; Infant; Inflammation; Interleukin-1beta; Interleukin-6; Ionomycin; Leukocyte Count; Leukocytes; Lipopolysaccharides; Male; Peptidoglycan; Prospective Studies; Tetradecanoylphorbol Acetate; Tumor Necrosis Factor-alpha

Previously, we reported that heat shock protein (HSP)65 impairs the effects of high-density lipoprotein on macrophages. We also showed that immune response activation adversely affects reverse cholesterol transport (RCT). In this study, we investigated the effects of the Src family kinase lymphocyte-specific protein tyrosine kinase (Lck) and elucidated the mechanism underlying HSP65-regulated cholesterol efflux in T cells. We evaluated cell proliferation, Lck expression, and inflammatory cytokine production in Jurkat cells and CD4

Topics: ATP Binding Cassette Transporter 1; ATP Binding Cassette Transporter, Subfamily G, Member 1; Biological Transport; Calcium; CD4-Positive T-Lymphocytes; Cell Proliferation; Cholesterol; Cytokines; Heat-Shock Proteins; Humans; Inflammation; Ionomycin; Jurkat Cells; Lymphocyte Activation; Lymphocyte Specific Protein Tyrosine Kinase p56(lck); MAP Kinase Signaling System; NF-kappa B; Phosphorylation; PPAR gamma; Pyrimidines; Receptors, Antigen, T-Cell; Scavenger Receptors, Class B; Signal Transduction; T-Lymphocytes

Interleukin (IL)-17 represents a family of cytokines with six members, namely IL-17A, B, C, D, E, and F. IL-17A and IL-17F are best studied proinflammatory cytokines. CD4(+) T helper cells producing IL-17A have been identified as a distinct T helper subset, Th17 cells. IL-17 and Th17 cells are important mediators in tissue inflammation in immune-mediated inflammatory diseases. IL-17 is also produced by other immune cells and plays an important role in host defense against microbial infection. Cell-based assays are sensitive and quantitative, and enable identification of cellular sources of IL-17 production. This chapter describes usage of flow cytometry and ELISPOT assays to quantify IL-17A-producing cells in disease and in vitro experiments to study T cell function.

Topics: Animals; Antibodies; Brefeldin A; Enzyme-Linked Immunospot Assay; Female; Flow Cytometry; Fluorescein-5-isothiocyanate; Fluorescent Dyes; Humans; Inflammation; Interleukin-17; Interleukin-6; Ionomycin; Mice; Mice, Inbred C57BL; Phycoerythrin; Quinolinium Compounds; Tetradecanoylphorbol Acetate; Th17 Cells; Transforming Growth Factor beta

A rise in intracellular Ca(2+) ([Ca(2+)](i)) is crucial for the activation of macrophages, however, the mechanisms and consequences of this [Ca(2+)](i) increase remain unclear. This study investigated the role of calcium in mouse peritoneal macrophages stimulated with LPS plus IFN-γ by using the store-operated Ca(2+) channel (SOCC) blocker SK&F 96365. Our results showed that SK&F 96365 pretreatment significantly inhibited the elevation of [Ca(2+)](i) induced by ionomycin, thapsigargin, and LPS plus IFN-γ, respectively. Phagocytosis analyzing results showed that SK&F 96365 efficiently diminished the uptake of nonopsonized 1 μM yellow-green beads or pHrodo™-labeled Escherichia coli bacteria both on the resting and LPS plus IFN-γ-stimulated macrophages. In addition, SK&F 96365 significantly inhibited the LPS plus IFN-γ-induced brisk uptake of NO and ROS. The CBA analyzing results showed that SK&F 96365 pretreatment efficiently inhibited the production of LPS plus IFN-γ-induced inflammatory cytokines of IL-6, MCP-1, TNF, INF-γ, and IL-10. However, SK&F 96365 pretreatment did not inhibit but augment the production of LPS plus IFN-γ-induced IL-1β secretion. Furthermore, SK&F 96365 pretreatment inhibited the LPS plus IFN-γ-induced translocation of NF-κB to the nucleus, and induced a decrease in mitochondrial membrane potential (ΔΨm) in LPS plus IFN-γ-activated macrophages. This study provides insight into the role of calcium in the activation of peritoneal macrophages induced by LPS plus IFN-γ, and blocking the calcium influx by SK&F 96365 exhibited a domain inhibitory effect on the LPS plus IFN-γ-induced inflammatory response in macrophages.

Topics: Animals; Calcium; Calcium Channel Blockers; Calcium Channels; Cells, Cultured; Chemokine CCL2; Escherichia coli; Female; Imidazoles; Inflammation; Interferon-gamma; Interleukin-10; Interleukin-1beta; Interleukin-6; Ionomycin; Lipopolysaccharides; Macrophages, Peritoneal; Membrane Potential, Mitochondrial; Mice; Mice, Inbred BALB C; NF-kappa B; Nitric Oxide; Phagocytosis; Protein Transport; Reactive Oxygen Species; Thapsigargin; Tumor Necrosis Factor-alpha

The purpose of the current study is to examine the surface expression of chemokine receptors and the chemotaxis toward the respective chemokines of glatiramer acetate (GA)-specific CD4(+) T cells isolated from the blood and the cerebrospinal fluid (CSF) of a multiple sclerosis (MS) patient. Four clones were selected, two isolated from the peripheral blood and two from the CSF. CCR4 and CXCR3 were expressed on all four clones. Both blood-derived clones also expressed CCR5 and, to a lesser extent, CCR6. Similarly, one CSF clone expressed CCR5 and CCR6. In contrast, CCR1, CCR2, CCR3, CCR7, CCR9, CCR10, CXCR1, CXCR4, CXCR5, CXCR6, and CCR6 were either expressed on few cells or were not expressed at all on all four clones examined. The expression of chemokine receptors was corroborated with the ability of the cells to respond chemotactically to the corresponding chemokines, CCL5/RANTES, CCL20/MIP-3α, CCL22/MDC and CXCL10/IP-10. Both the receptor expression and chemotaxis were reduced upon activation with PMA and ionomycin. The shared expression of chemokine receptors and the migration patterns suggest that GA-reactive cells have migrated from the blood into the CSF, and that local reactivation within the inflamed CSF may downregulate the expression of chemokine receptors and hence impede their migration intrathecally. The results may also explain the beneficial synergistic effects of combining immunosuppressive drugs with GA in MS patients.

Topics: Adult; Blood; CD4-Positive T-Lymphocytes; Cell Movement; Cells, Cultured; Cerebrospinal Fluid; Chemokines; Chemotaxis, Leukocyte; Flow Cytometry; Gene Expression; Glatiramer Acetate; Humans; Inflammation; Ionomycin; Lymphocyte Activation; Male; Multiple Sclerosis, Relapsing-Remitting; Peptides; Receptors, CCR4; Receptors, CCR5; Receptors, CCR6; Receptors, CXCR3; Signal Transduction; Tetradecanoylphorbol Acetate

SK&F 96365, 51-(beta-[3-(p-methoxyphenyl)-propyloxy]-p-methoxyphenethyl)-1H-imidazole hydrochloride, has emerged as a useful pharmacological tool in the study of store-operated Ca²⁺ entry (SOCE). But the precise molecular mechanism and effect of SK&F 96365 on mouse lymphocytes are still not well determined. This study investigated the pharmacological profile of SK&F 96365 on mouse lymphocytes stimulated by mitogen concanavalin A (Con A) or by a combination of a protein kinase C (PKC) activator, phorbol 12-myristate 13-acetate (PMA) and a calcium ionophore, ionomycin in vitro. Our results showed that SK&F 96365 pre-treatment diminished the cytosolic calcium rise on lymphocytes induced by ionomycin, PMA/ionomycin, and thapsigargin (TG), respectively. CFDA-SE staining results showed that SK&F 96365 (5-20 μM) inhibited both Con A- and PMA/ionomycin-induced lymphocytes proliferation in a time- and dose-dependent manner. Upon the same stimulation, SK&F 96365 inhibited the expression of CD69 and CD25 on CD3⁺ T lymphocytes in a dose-dependent manner. The cell cycle analyzing results showed that SK&F 96365 caused a G0/G1 phase cell cycle arrest on both Con A- and PMA/ionomycin-activated lymphocytes in a dose-dependent manner. In addition, SK&F 96365 induced a decrease in mitochondrial membrane potential (ΔΨm) and promoted mitochondrial permeability transition (MPT) in both Con A- and PMA/ionomycin-activated lymphocytes. Furthermore, SK&F 96365 significantly inhibited the production of proinflammatory cytokines (interferon (IFN)-γ and tumor necrosis factor (TNF)), and the anti-inflammatory cytokine (IL-10) on both Con A- and PMA/ionomycin-activated lymphocytes. SK&F 96365 did not induce a statistically significant increase in levels of proinflammatory IL-6 and monocyte chemoattractant protein-1 (MCP-1) but of IL-12p70 upon the stimulation of Con A, whereas these three cytokines were markedly inhibited by it upon the stimulation of PMA/ionomycin. This finding revealed that SK&F 96365 exhibited an anti-inflammatory effect on mouse lymphocytes both upon the stimulation of Con A and PMA/ionomycin, and the precise mechanism of SK&F 96365 inhibiting Con A-activated lymphocytes proliferation is different from PMA/ionomycin.

Topics: Animals; Anti-Inflammatory Agents; Antigens, CD; Calcium; Calcium Channel Blockers; Calcium Channels; Cell Cycle; Cell Proliferation; Cells, Cultured; Concanavalin A; Cytokines; Dose-Response Relationship, Drug; Female; Fluoresceins; Fluorescent Dyes; Imidazoles; Inflammation; Ionomycin; Lymphocyte Activation; Lymphocyte Count; Membrane Potential, Mitochondrial; Mice; Mice, Inbred BALB C; Mitochondria; Signal Transduction; Succinimides; T-Lymphocytes; Tetradecanoylphorbol Acetate; Thapsigargin

IL-33 is a recently characterized IL-1 family cytokine and found to be expressed in inflammatory diseases, including severe asthma and inflammatory bowl disease. Recombinant IL-33 has been shown to enhance Th2-associated immune responses and potently increase mast cell proliferation and cytokine production. While IL-33 is constitutively expressed in endothelial and epithelial cells, where it may function as a transcriptional regulator, cellular sources of IL-33 and its role in inflammation remain unclear.. Here, we identify mast cells as IL-33 producing cells. IgE/antigen activation of bone marrow-derived mast cells or a murine mast cell line (MC/9) significantly enhanced IL-33. Conversely, recombinant IL-33 directly activated mast cells to produce several cytokines including IL-4, IL-5 and IL-6 but not IL-33. We show that expression of IL-33 in response to IgE-activation required calcium and that ionomycin was sufficient to induce IL-33. In vivo, peritoneal mast cells expressed IL-33 and IL-33 levels were significantly lower within the skin of mast cell deficient mice, compared to littermate controls. Local activation of mast cells promotes edema, followed by the recruitment of inflammatory cells. We demonstrate using passive cutaneous anaphylaxis, a mast cell-dependent model, that deficiency in ST2 or antibody blockage of ST2 or IL-33 ablated the late phase inflammatory response but that the immediate phase response was unaffected. IL-33 levels in the skin were significantly elevated only during the late phase.. Our findings demonstrate that mast cells produce IL-33 after IgE-mediated activation and that the IL-33/ST2 pathway is critical for the progression of IgE-dependent inflammation.

Topics: Animals; Antigens; Bone Marrow Cells; Calcium; Female; Gene Expression Regulation; Humans; Immunoglobulin E; Inflammation; Interleukin-1 Receptor-Like 1 Protein; Interleukin-33; Interleukins; Ionomycin; Mast Cells; Mice; Rats; Receptors, Interleukin

Here we studied and characterized different peripheral blood (PB) regulatory T cell (Treg) subsets in rheumatoid arthritis (RA) patients and tested the hypothesis that changes in these cells can be linked to the degree of inflammation and relapsing/remission periods. PB cells were examined from RA subjects (n = 60) with different disease activity score-28 (DAS28) and from healthy controls (n = 40). Frequencies of Treg subsets expressing characteristic membrane antigens, FoxP3 or intracellular cytokines were quantified by flow cytometry. We observed a decrease in the percentages of CD4(+)CD25(high), CD4(+)CD25(int), CD4(+)CD25(int/high)FoxP3(+), CD4(+)CD38(+), CD4(+)CD62L(+), CD8(+)CD25(high)CD45RA(+) and CD8(+)CD25(int)CD45RA(+) T cells in PB of RA patients compared to healthy controls. In addition, we found increased percentages of cells expressing membrane/intracellular regulatory antigens such as OX40 (CD134), CD45RB(low) or CTLA-4 (CD152), and a higher proportion of other T cell subsets including CD4(+)CTLA-4(+), CD4(+)IL10(+), CD4(+)CD25(int)IL10(+), CD4(+)CD25(int) TGFbeta(+), CD4(+)CD25(low) TGFbeta(+) and CD8(+)CD28(- ). We show that most of these changes parallel the intensity of inflammation, with lowest or highest values in patients with moderately/very active disease compared to healthy controls and at times to patients with inactive RA. The balance between these cell subsets and their antigen expression would determine the inflammation levels and could thus be linked to the relapsing/remission periods of the disease.

Topics: Aged; Antigens, CD; Arthritis, Rheumatoid; CD4 Lymphocyte Count; CTLA-4 Antigen; Female; Forkhead Transcription Factors; Humans; Immunophenotyping; Inflammation; Interferon-gamma; Interleukin-10; Interleukin-2 Receptor alpha Subunit; Ionomycin; Male; Middle Aged; Recurrence; T-Lymphocyte Subsets; T-Lymphocytes, Regulatory; Tetradecanoylphorbol Acetate; Transforming Growth Factor beta

Inflammatory responses by mast cells are characterized by massive exocytosis of prestored granular mediators followed by cytokine/chemokine release. The vesicular trafficking mechanisms involved remain poorly understood. Vesicular-associated membrane protein-8 (VAMP-8), a member of the soluble N-ethylmaleimide-sensitive factor (NSF) attachment protein receptor (SNARE) family of fusion proteins initially characterized in endosomal and endosomal-lysosomal fusion, may also function in regulated exocytosis. Here we show that in bone marrow-derived mast cells (BMMCs) VAMP-8 partially colocalized with secretory granules and redistributed upon stimulation. This was associated with increased SNARE complex formation with the target t-SNAREs, SNAP-23 and syntaxin-4. VAMP-8-deficient BMMCs exhibited a markedly reduced degranulation response after IgE+ antigen-, thapsigargin-, or ionomycin-induced stimulation. VAMP-8-deficient mice also showed reduced plasma histamine levels in passive systemic anaphylaxis experiments, while cytokine/chemokine release was not affected. Unprocessed TNF accumulated at the plasma membrane where it colocalized with a VAMP-3-positive vesicular compartment but not with VAMP-8. The findings demonstrate that VAMP-8 segregates secretory lysosomal granule exocytosis in mast cells from cytokine/chemokine molecular trafficking pathways.

Topics: Anaphylaxis; Animals; Antigens; Cell Degranulation; Cytokines; Exocytosis; Histamine; Immunoglobulin E; Inflammation; Ionomycin; Ionophores; Lactones; Lysosomes; Mast Cells; Membrane Fusion; Mice; Mice, Knockout; Protein Transport; Qa-SNARE Proteins; Qb-SNARE Proteins; R-SNARE Proteins; Secretory Vesicles; Thapsigargin

Airway pathologies have been comprehensively researched in adult asthma, but in children, the extent of airway inflammation associated with episodic wheeze, often diagnosed as asthma, has not been fully characterized. It is not clear whether persistent airway inflammation is present in the absence of wheezing symptoms, and there is controversy regarding the role of age and atopy. This study assessed cellular and cytokine markers of airway inflammation in asymptomatic children with a history of episodic wheeze. Children with a history of episodic wheeze and cough (study group) and nonasthmatic patients requiring elective surgery (control group) were recruited. All subjects in the study group had a history of significant episodic wheezing (>2 episodes per year), and used only as-needed beta-agonist treatment. Bronchoalveolar lavage (BAL) was obtained using bronchoscopic lavage (study group) and nonbronchoscopic lavage (control group). Differential cell counts of BAL and flow cytometry were performed to identify T-lymphocyte phenotypes, and intracellular cytokine profiles were measured after phorbol-12-myristate 13-acetate (PMA) stimulation of BAL fluid T-cells. Twenty-one children with a history of 2-12 episodes of wheeze per year and 21 nonasthmatic subjects without respiratory symptoms were recruited. Study and control subjects were matched for age (median age, 5 years) and demographic characteristics. Study subjects had higher IgE levels, but their measurements were still within normal range. No significant differences in BAL differential cell counts were noted, and in both groups, the majority of T-cells were CD3+ CD8+, with a median CD4:CD8 ratio of 0.6. There was no significant difference in T-cell expression of the activation markers HLA-DR and CD25 (IL-2 receptor), or in PMA-induced production of the intracellular cytokines IFN-gamma, IL-2, IL-4, IL-5, and IL-10. The results of this study suggest that significant T-cell-driven airway inflammation is absent in mild or nonatopic, asymptomatic children of this age group who have episodic wheeze. Our findings support asthma management guidelines that do not recommend long-term treatment of this group of patients with anti-inflammatory medications.

Topics: Asthma; Brefeldin A; Bronchi; Bronchoalveolar Lavage Fluid; CD3 Complex; CD4-Positive T-Lymphocytes; Cell Count; Child; Child, Preschool; Eosinophils; Female; HLA-DR Antigens; Humans; Immunoglobulin E; Inflammation; Interferon-gamma; Interleukin-2 Receptor alpha Subunit; Interleukins; Ionomycin; Lymphocytes; Male; Neutrophils; Respiratory Sounds; T-Lymphocyte Subsets; Tetradecanoylphorbol Acetate

We have isolated a novel soluble factor(s), neutrophil activator of matrix metalloproteinases (NAM), secreted by unstimulated normal human peripheral blood neutrophils that causes the activation of cell secreted promatrix metalloproteinase-2 (proMMP-2). Partially purified preparations of NAM have been isolated from the conditioned media of neutrophils employing gelatin-Sepharose chromatography and differential membrane filter centrifugation. NAM activity, as assessed by exposing primary human umbilical vein endothelial cells (HUVEC) or HT1080 cells to NAM followed by gelatin zymography, was seen within one hour. Tissue inhibitor of metalloproteinase-2 (TIMP-2) and hydroxamic acid derived inhibitors of MMPs (CT1746 and BB94) abrogated the activation of proMMP-2 by NAM, while inhibitors of serine and cysteine proteases showed no effect. NAM also produced an increase in TIMP-2 binding to HUVEC and HT1080 cell surfaces that was inhibited by TIMP-2, CT1746, and BB94. Time-dependent increases in MT1-MMP protein and mRNA were seen following the addition of NAM to cells. These data support a role for NAM in cancer dissemination.

Topics: Adult; Amides; Calcimycin; Cathepsin G; Cathepsins; Cells, Cultured; Culture Media, Conditioned; Endothelium, Vascular; Enzyme Activation; Enzyme Precursors; Humans; Inflammation; Ionomycin; Matrix Metalloproteinase 14; Matrix Metalloproteinase 2; Neoplasm Invasiveness; Neoplasm Metastasis; Neutrophils; Oligopeptides; Pancreatic Elastase; Phenylalanine; Protease Inhibitors; Proteins; RNA, Messenger; Serine Endopeptidases; Substrate Specificity; Tetradecanoylphorbol Acetate; Thiophenes; Tissue Inhibitor of Metalloproteinase-2; Umbilical Veins

The role of a cytosolic phospholipase A(2)-alpha (cPLA(2)-alpha) in neutrophil arachidonic acid release, platelet-activating factor (PAF) biosynthesis, NADPH oxidase activation, and bacterial killing in vitro, and the innate immune response to bacterial infection in vivo was examined. cPLA(2)-alpha activity was blocked with the specific cPLA(2)-alpha inhibitor, Pyrrolidine-1 (human cells), or by cPLA(2) -alpha gene disruption (mice). cPLA(2)-alpha inhibition or gene disruption led to complete suppression of neutrophil arachidonate release and PAF biosynthesis but had no effect on neutrophil NADPH oxidase activation, FcgammaII/III or CD11b surface expression, primary or secondary granule secretion, or phagocytosis of Escherichia coli in vitro. In contrast, cPLA(2)-alpha inhibition or gene disruption diminished neutrophil-mediated E. coli killing in vitro, which was partially rescued by exogenous arachidonic acid or PAF but not leukotriene B(4). Following intratracheal inoculation with live E. coli in vivo, pulmonary PAF biosynthesis, inflammatory cell infiltration, and clearance of E. coli were attenuated in cPLA(2)-alpha(-/-) mice compared with wild type littermates. These studies identify a novel role for cPLA(2)-alpha in the regulation of neutrophil-mediated bacterial killing and the innate immune response to bacterial infection.

Topics: Animals; Arachidonic Acid; Bronchoalveolar Lavage Fluid; CD11b Antigen; Cytosol; Dose-Response Relationship, Drug; Escherichia coli; Group IV Phospholipases A2; Humans; Inflammation; Ionomycin; Leukotriene B4; Mice; Mice, Transgenic; NADPH Oxidases; Neutrophils; Oxygen; Phagocytosis; Phospholipases A; Phospholipases A2; Platelet Activating Factor; Pneumonia; Pyrrolidines; Receptors, IgG; Time Factors; Tumor Necrosis Factor-alpha

Interaction of macrophages with apoptotic cells involves multiple steps including recognition, tethering, phagocytosis, and anti-inflammatory macrophage responses. Defective apoptotic cell clearance is associated with pathogenesis of autoimmune disease. CD14 is a surface receptor that functions in vitro in the removal of apoptotic cells by human and murine macrophages, but its mechanism of action has not been defined. Here, we demonstrate that CD14 functions as a macrophage tethering receptor for apoptotic cells. Significantly, CD14(-/-) macrophages in vivo are defective in clearing apoptotic cells in multiple tissues, suggesting a broad role for CD14 in the clearance process. However, the resultant persistence of apoptotic cells does not lead to inflammation or increased autoantibody production, most likely because, as we show, CD14(-/-) macrophages retain the ability to generate anti-inflammatory signals in response to apoptotic cells. We conclude that CD14 plays a broad tethering role in apoptotic cell clearance in vivo and that apoptotic cells can persist in the absence of proinflammatory consequences.

Topics: Animals; Apoptosis; Autoimmune Diseases; Cell Line, Tumor; COS Cells; Dexamethasone; Humans; Inflammation; Ionomycin; Lipopolysaccharide Receptors; Macrophages; Mice; Mice, Inbred BALB C; Mice, Knockout; Thymus Gland; Time Factors

Intercellular adhesion molecule 3 (ICAM-3) has recently been identified on the surface of eosinophils.. The purpose of this study was to characterize ICAM-3 expression on eosinophils in response to cytokines and to determine whether ligand binding of ICAM-3 modulates inflammatory responses of eosinophils, as it does in other leukocytes.. To determine effects of ICAM-3 on eosinophil function, we isolated human eosinophils and used a monoclonal antibody directed against the epitope of ICAM-3 that binds to leukocyte-function antigen-1 to mimic binding of ICAM-3 and this natural ligand. We measured granulocyte-macrophage colony stimulating factor (GM-CSF) production by unstimulated eosinophils and eosinophils stimulated with ionomycin (1 micromol/L), both in the presence and absence of this anti-ICAM-3 antibody.. We found that 99% of eosinophils expressed ICAM-3, regardless of whether allergic symptoms were present or absent. Expression of ICAM-3 was not enhanced by proinflammatory cytokines. Expression of ICAM-3 was reduced in apoptotic cells and in cells incubated with the combination of GM-CSF and tumor necrosis factor-alpha (n = 3). Antibody binding of ICAM-3, which mimics leukocyte-function antigen-1 binding, had no effect on baseline GM-CSF production but reduced by 80% the production of GM-CSF stimulated by ionomycin (control 1969 pg/mL +/- 1259 SD versus anti-ICAM-3 396 pg/mL +/- 207 SD, n = 8) and reduced GM-CSF mRNA content.. ICAM-3 is highly expressed on the surface of human eosinophils, and downregulation of GM-CSF production by anti-ICAM-3 mAb suggests that ICAM-3 ligation may inhibit eosinophil inflammatory responses and survival.

Topics: Adult; Cell Adhesion Molecules; Cytokines; Eosinophils; Gene Expression Regulation; Granulocyte-Macrophage Colony-Stimulating Factor; Humans; Inflammation; Intercellular Adhesion Molecule-1; Ionomycin; Middle Aged; RNA, Messenger

Resistance to recombinant human erythropoietin occurs in a small but important proportion of hemodialysis patients. This may be due to increased immune activation because pro-inflammatory cytokines inhibit erythropoiesis in vitro. Using FACScan flow cytometry, the proportion of PMA/ionomycin-stimulated T cells expressing cytokines ex vivo was compared in 18 poor responders to erythropoietin, 14 good responders to erythropoietin, and 14 normal controls. CD4(+) T cells from poor responders expressed more interferon-gamma (IFN-gamma; 19 +/- 6%) compared with good responders (11 +/- 6%, P < 0.001) and controls (12 +/- 6%, P < 0.01). Similarly, CD4+ T cells from poor responders expressed more tumor necrosis factor-alpha (TNF-alpha; poor responders: 51 +/- 19% versus good responders: 27 +/- 15% [P < 0.01] and controls: 30 +/- 19% [P < 0.01]). CD4+ expression of IL-10 was also enhanced (poor responders: 1.6 +/- 1.1% versus good responders: 0.7 +/- 0.6% [P < 0.05] and controls: 0.5 +/- 0.2% [P < 0.01]). Likewise, CD4+ expression of interleukin-13 (IL-13) was increased (poor responders: 4.4 +/- 4.2% versus good responders: 1.6 +/- 1.7% [P < 0.05] and controls: 1.6 +/- 1.5% [P < 0.05]). CD8+ T cells from poor responders also showed enhanced expression of cytokines. For IFN-gamma, poor responder expression was 48 +/- 20% compared with 31 +/- 17% (P < 0.05) for good responders and 23 +/- 15% (P < 0.01) for controls. TNF-alpha expression for poor responders was 41 +/- 21% versus 25 +/- 14% for good responders (P < 0.05) and 21 +/- 15% for controls (P < 0.01). IL-10 expression for poor responders was 2.0 +/- 1.2% (good responders: 0.7 +/- 0.6% [P < 0.01]; controls: 0.5 +/- 0.2% [P < 0.001]). These data indicate that T cells from poor responders are in an enhanced activation state possibly as a result of chronic inflammation. In the absence of any other cause (such as iron deficiency), the overproduction of cytokines may account for hyporesponsiveness to erythropoietic therapy in patients with renal failure.

Topics: Adult; Aged; Angiotensin-Converting Enzyme Inhibitors; Case-Control Studies; CD4-Positive T-Lymphocytes; CD8-Positive T-Lymphocytes; Cell Division; Cell Separation; Cytokines; Erythropoiesis; Erythropoietin; Female; Flow Cytometry; Humans; Inflammation; Interferon-gamma; Interleukin-10; Interleukin-13; Interleukin-4; Ionomycin; Leukocytes, Mononuclear; Lymphocyte Activation; Male; Middle Aged; Models, Biological; Recombinant Proteins; Reproducibility of Results; T-Lymphocytes; Time Factors; Treatment Outcome; Tumor Necrosis Factor-alpha

In pathological situations, different modes of cell death are observed, and information on the role and uptake of nonapoptotic corpses is scarce. Here, we modeled two distinct forms of death in human Jurkat T cells treated with staurosporine: classical apoptosis under normal culture conditions and programmed death with necrotic morphology under ATP-depleting conditions (necPCD). When offered to phagocytes, both types of cell corpses (but not heat-killed unscheduled necrotic cells) reduced the release of the proinflammatory cytokine TNF from the macrophages. The necPCD cells were efficiently engulfed by macrophages and microglia, and from mixtures of necPCD and apoptotic cells macrophages preferentially engulfed the necrotic cells. Using a newly developed assay, we demonstrated that phosphatidylserine is translocated to the surface of such necrotic cells. We demonstrate that this can occur independently of calcium signals, and that surface phosphatidylserine is essential for the uptake of necrotic cells by both human macrophages and murine microglia.

Topics: Animals; Annexin A5; Antibodies, Monoclonal; Apoptosis; Calcium; CD36 Antigens; Cell Line; Cell Membrane; Cells, Cultured; Escherichia coli; Formaldehyde; Humans; Inflammation; Ionomycin; Jumonji Domain-Containing Histone Demethylases; Jurkat Cells; Lipopolysaccharide Receptors; Liposomes; Macrophages; Membrane Lipids; Mice; Microglia; Microscopy, Confocal; Microscopy, Fluorescence; Necrosis; Oligomycins; Oligopeptides; Phagocytosis; Phosphatidylserines; Polymers; Receptors, Cell Surface; Staurosporine; Tumor Necrosis Factor-alpha

In this study, we investigated whether luteolin monoglucuronide was converted to free aglycone during inflammation using human neutrophils stimulated with ionomycin/cytochalasin B and rats treated with lipopolysaccharide (LPS). beta-Glucuronidase activity was assayed using 4-methylumbelliferyl-glucuronide and methanol extracts of rat plasma containing luteolin monoglucuronide. The released 4-methylumbelliferone, a fluorescent molecule, was quantified by fluorometry. Deglucuronidation of luteolin monoglucuronide was examined by high-performance liquid chromatography (HPLC) analysis. HPLC analyses showed that the supernatants obtained from neutrophils stimulated with ionomycin/cytochalasin B hydrolyzed luteolin monoglucuronide to free luteolin. beta-Glucuronidase activity in human serum from patients on hemodialysis increased significantly compared with that from healthy volunteers. The beta-glucuronidase activity in rat plasma increased after i.v. injection of LPS. The ratio of luteolin to luteolin monoglucuronide in plasma of LPS-treated rats also increased. These results suggest that during inflammation beta-glucuronidase is released from stimulated neutrophils or certain injured cells and then deglucuronidation of flavonoids occurs.

Topics: Animals; Chromatography, High Pressure Liquid; Cytochalasin B; Expectorants; Flavonoids; Glucuronidase; Glucuronides; Humans; In Vitro Techniques; Inflammation; Ionomycin; Ionophores; Lipopolysaccharides; Luteolin; Neutrophils; Rats; Rats, Sprague-Dawley

Leukocytes extravasate from the blood in response to physiologic or pathologic demands by means of complementary ligand interactions between leukocytes and endothelial cells. The multistep model of leukocyte extravasation involves an initial transient interaction ("rolling" adhesion), followed by secondary (firm) adhesion. We recently showed that binding of CD44 on activated T lymphocytes to endothelial hyaluronan (HA) mediates a primary adhesive interaction under shear stress, permitting extravasation at sites of inflammation. The mechanism for subsequent firm adhesion has not been elucidated. Here we demonstrate that the integrin VLA-4 is used in secondary adhesion after CD44-mediated primary adhesion of human and mouse T cells in vitro, and by mouse T cells in an in vivo model. We show that clonal cell lines and polyclonally activated normal T cells roll under physiologic shear forces on hyaluronate and require VCAM-1, but not ICAM-1, as ligand for subsequent firm adhesion. This firm adhesion is also VLA-4 dependent, as shown by antibody inhibition. Moreover, in vivo short-term homing experiments in a model dependent on CD44 and HA demonstrate that superantigen-activated T cells require VLA-4, but not LFA-1, for entry into an inflamed peritoneal site. Thus, extravasation of activated T cells initiated by CD44 binding to HA depends upon VLA-4-mediated firm adhesion, which may explain the frequent association of these adhesion receptors with diverse chronic inflammatory processes.

Topics: Animals; Cell Adhesion; Cell Movement; Endothelium, Vascular; Humans; Hyaluronan Receptors; Hyaluronic Acid; Inflammation; Integrin alpha4beta1; Integrins; Ionomycin; Lymphocyte Activation; Lymphocyte Function-Associated Antigen-1; Mice; Receptors, Lymphocyte Homing; Stress, Mechanical; T-Lymphocytes; Tetradecanoylphorbol Acetate; Vascular Cell Adhesion Molecule-1

Many systemically effective drugs such as cyclosporin A are ineffective topically because of their poor penetration into skin. To surmount this problem, we conjugated a heptamer of arginine to cyclosporin A through a pH-sensitive linker to produce R7-CsA. In contrast to unmodified cyclosporin A, which fails to penetrate skin, topically applied R7-CsA was efficiently transported into cells in mouse and human skin. R7-CsA reached dermal T lymphocytes and inhibited cutaneous inflammation. These data establish a general strategy for enhancing delivery of poorly absorbed drugs across tissue barriers and provide a new topical approach to the treatment of inflammatory skin disorders.

Topics: Administration, Topical; Animals; Arginine; Biological Transport; Biotinylation; Cyclosporine; Cyclosporins; Humans; Inflammation; Interleukin-2; Ionomycin; Jurkat Cells; Mice; Mice, Inbred BALB C; Molecular Structure; Prodrugs; Skin; Skin Absorption; Tetradecanoylphorbol Acetate

CD40L expression is well recognized to be of critical importance in initiation of the immune response. Because cAMP mediates actions of bronchodilators commonly used in asthma, the effects of cAMP in regulating the immune response are of major importance. Cyclic AMP was found to either inhibit or markedly increase CD40L expression dependent upon the mechanisms of T cell activation. Cyclic AMP inhibited CD40L expression induced by TCR activation. In contrast, cAMP enhanced CD40L induced by CD2-mediated T cell activation or by calcium-dependent mechanisms. While neither CD28 costimulation nor exogenous IL-2 or IL-4 prevented cAMP inhibition in TCR activated cells, addition of calcium ionophore to TCR activation prevented any inhibitory effects and caused cAMP to increase CD40L expression. Actions of cAMP to increase CD40L expression appeared independent of PKC and were not a reflection of generalized cellular activation since neither CD25 nor CD69 expression was affected. The markedly contrasting actions of cAMP to decrease or increase CD40L expression, an important control point in the immune response, could be relevant to actions of commonly used medications including bronchodilators.

Topics: Calcium; CD2 Antigens; CD40 Ligand; Cells, Cultured; Cyclic AMP; Humans; Inflammation; Interleukin-2; Interleukin-4; Ionomycin; Membrane Glycoproteins; Protein Kinase C

Recent studies have demonstrated that pulmonary surfactant protein (SP)-A plays a potential role in modifying inflammation and immune function. To see whether SP-A could modify IL-8 production and release by eosinophils stimulated with ionomycin, SP-A purified from surfactant recovered from patients with alveolar proteinosis was added to eosinophils isolated by the negative-selection method with immunomagnetic beads, and cultured for 24 h. The concentrations of IL-8 in the cell-free supernatants and cell lysates were then measured by ELISA. SP-A attenuated the production of IL-8 by eosinophils in a concentration-dependent manner. SP-A also attenuated the release of IL-8 from the eosinophils. The addition of SP-A antibody (PE10) reversed these effects of SP-A completely. These data suggest that SP-A may have the potential to modify allergic inflammation by inhibiting the release and production of IL-8 by eosinophils.

Topics: Antibodies, Monoclonal; Asthma; Dose-Response Relationship, Drug; Eosinophils; Humans; In Vitro Techniques; Inflammation; Interleukin-8; Ionomycin; Lung; Proteolipids; Pulmonary Surfactant-Associated Protein A; Pulmonary Surfactant-Associated Proteins; Pulmonary Surfactants

To determine functional responses of neonatal chicken and turkey heterophils to various inflammatory agonists.. 100 one-day-old chickens and turkeys.. Blood heterophils were isolated and stimulated for 30 minutes at 39 C with ionomycin, phorbol myristate acetate (PMA), opsonized zymosan (OZ), or formyl-methionyl-leucyl-phenylalanine (FMLP). Functional responses (shape change, adherence, phagocytosis, influx of intracellular calcium, and oxidative burst) of stimulated heterophils were measured and compared with responses of unstimulated (control) heterophils.. Turkey and chicken heterophils did not respond to FMLP stimulation. Stimulation of chicken and turkey heterophils with ionomycin resulted in significant increases in adherence, percentage of cells with a shape change, phagocytosis, intracellular calcium concentration, and oxidative burst. Turkey heterophils did not respond to PMA stimulation, whereas stimulation of chicken heterophils with PMA resulted in significant increases in adherence, percentage of cells with a shape change, phagocytosis, and oxidative burst but not intracellular calcium concentration. Stimulation of chicken and turkey heterophils with OZ resulted in significant increases in oxidative burst.. Mechanisms regulating initiation of heterophil activation in neonatal chicken and turkey heterophils are consistent with those described for heterophils isolated from mature birds. The biochemical and cytoskeletal systems of neonatal avian heterophils undergo functional alterations following stimulation with inflammatory agonists.. Understanding heterophil activation and regulation should eventually lead to methods for controlling bacterial diseases in poultry.

Topics: Animals; Calcium; Cell Adhesion; Chickens; Immunity, Innate; Inflammation; Ionomycin; Luminescent Measurements; N-Formylmethionine Leucyl-Phenylalanine; Phagocytosis; Poultry Diseases; Respiratory Burst; Tetradecanoylphorbol Acetate; Turkeys

Activation of the NFkappaB transcription factor in 16HBE human bronchial epithelial cells was compared with activation of NFkappaB in Jurkat T-cells. An NFkappaB-luciferase reporter gene was activated by phorbol myristyl acetate (PMA) in both cell types. Ionomycin added to PMA (P/I) inhibited NFkappaB activation in epithelial cells and enhanced PMA activation in T-cells. Cyclosporin A (CsA) inhibited calcium signaling in both cell types. Nuclear NFkappaB DNA-binding stimulated with PMA was inhibited with ionomycin in epithelial cells and was enhanced with ionomycin in T-cells; CsA reversed both effects of ionomycin. Cytosolic IkappaB-alpha was regulated identically in both cell types. Thus, calcium activated opposing nuclear signaling pathways in epithelial cells and T-cells. Calcium-mediated repression of NFkappaB in epithelial cells was derepressed by CsA, and this establishes a mechanism through which CsA may exert proinflammatory effects in nonlymphoid cells.

Topics: Base Sequence; Bronchi; Calcium; Cell Line, Transformed; Cyclosporine; Epithelium; Genes, Reporter; Humans; Inflammation; Ionomycin; Jurkat Cells; Luciferases; NF-kappa B; Oligonucleotide Probes; Signal Transduction; Tacrolimus; Tetradecanoylphorbol Acetate; Transcriptional Activation; Transfection

Endothelial cell (EC) cytoskeletal proteins are one of the earliest primary targets of second messenger cascades generated in response to inflammatory agonists. Actin binding proteins, by modulating actin gelation-solation state and membrane-cytoskeleton interactions, in part regulate cell motility and cell-cell apposition. This in turn can also modulate interendothelial junctional diameter and permeability. Nonmuscle filamin (ABP-280), a dimeric actin-crosslinking protein, promotes orthogonal branching of F-actin and links microfilaments to membrane glycoproteins. In the present study, immunoblot analysis demonstrates that filamin protein levels are low in sparse EC cultures, increase once cell-cell contact is initiated and then decrease slightly at post-confluency. Both bradykinin and ionomycin cause filamin redistribution from the peripheral cell border to the cytosol of confluent EC. Forskolin, an activator of adenylate cyclase, blocks filamin translocation. Bradykinin activation of EC is not accompanied by significant proteolytic cleavage of filamin. Instead, intact filamin is recycled back to the membrane within 5-10 min of bradykinin stimulation. Inhibitors of calcium/calmodulin dependent protein kinase (KT-5926 and KN-62) attenuate bradykinin-induced filamin translocation. H-89, an inhibitor of cAMP-dependent protein kinase, causes translocation of filamin in unstimulated cells. Calyculin A, an inhibitor of protein phosphatases, also causes translocation of filamin in the absence of an inflammatory agent. ML-7, an inhibitor of myosin light chain kinase and phorbol myristate acetate, an activator of protein kinase C, do not cause filamin movement into the cytosol, indicating that these pathways do not modulate the translocation. Pharmacological data suggest that filamin translocation is initiated by the calcium/calmodulin-dependent protein kinase whereas the cAMP-dependent protein kinase pathway prevents translocation. Inflammatory agents therefore may increase vascular junctional permeability by increasing cytoplasmic calcium, which disassembles the microfilament dense peripheral band by releasing filamin from F-actin.

Topics: Animals; Bradykinin; Calcium; Calcium-Calmodulin-Dependent Protein Kinase Type 2; Calcium-Calmodulin-Dependent Protein Kinases; Cattle; Cell Membrane; Cells, Cultured; Contractile Proteins; Cyclic AMP-Dependent Protein Kinases; Cytosol; Endothelium, Vascular; Filamins; Inflammation; Ionomycin; Ionophores; Microfilament Proteins; Phosphoprotein Phosphatases; Protein Kinases; Signal Transduction; Subcellular Fractions

A series of azachalcones was evaluated for ability to affect secretion of myeloperoxidase by rat polymorphonuclear leukocytes stimulated by fMLP. The compounds were found to interfere with cellular uptake of extracellular calcium. Structure-activity relationships are discussed.

Topics: Animals; Anti-Inflammatory Agents, Non-Steroidal; Calcium; Carrageenan; Fura-2; Inflammation; Ionomycin; Male; Manganese; Molecular Structure; N-Formylmethionine Leucyl-Phenylalanine; Neutrophils; Peroxidase; Pyridines; Rats; Rats, Sprague-Dawley; Structure-Activity Relationship

Both 2-lysophosphatidylcholine and cis-unsaturated fatty acids were previously shown to intensify agonist-induced cellular responses by enhancing the diacylglycerol-dependent activation of protein kinase C. Consistent with these observations, extracellular, secretory group II phospholipase A2, when added directly to human resting T lymphocytes, greatly potentiates their activation that was induced by a membrane-permeant diacylglycerol and ionomycin, as determined by the expression of the alpha subunit of the interleukin 2 receptor and thymidine incorporation into DNA. Diacylglycerol and ionomycin were essential for this cellular response, and phospholipase A2 alone showed no effect. The amount of 2-lysophosphatidylcholine produced in these cells by the exogenous phospholipase A2 was greatly increased in the presence of diacylglycerol and ionomycin, suggesting that the membrane phospholipids became susceptible to the phospholipase A2 when protein kinase C was activated. The results suggest that phospholipase A2 secreted into inflammatory sites plays a role in the propagation of cellular responses. Protein kinase C may function in the hydrolysis of membrane phospholipids by the exogenous phospholipase A2, and the products of this phospholipid hydrolysis enhance agonist-induced protein kinase C activation, thereby intensifying cellular responses.

Topics: Cell Membrane Permeability; Diglycerides; Dose-Response Relationship, Drug; Enzyme Activation; Humans; Inflammation; Ionomycin; Lymphocyte Activation; Lysophosphatidylcholines; Phospholipases A; Phospholipases A2; Protein Kinase C; Receptors, Interleukin-2; T-Lymphocytes