sq-23377 and Acute-Disease

Hepatitis E virus (HEV) infection is endemic in several developing countries. Clinical manifestations of this infection vary widely from asymptomatic infection to uncomplicated acute viral hepatitis and fulminant hepatic failure. The pathogenesis of this disease and the reason of varying disease severity remain unknown. In viral infections, tissue injury can be caused either by virus itself or by host immune responses directed against infected cells. We therefore studied adaptive immune responses to HEV antigens in patients with hepatitis E of varying disease severity and healthy controls.. Cytokine secreting CD4+ T cells and antibody-producing B cells specific for HEV were enumerated through intracellular cytokine staining and enzyme-linked immunosorbent spot assay, respectively.. Patients with fulminant hepatitis E had a less marked expansion of HEV-specific interferon-γ or tumor necrosis factor-a secreting CD4+ T cells than patients with uncomplicated hepatitis E and healthy controls. These patients also had fewer CD4+ T cells that produce γ-interferon or tumor necrosis factor-a upon in vitro polyclonal stimulation. In addition, patients with fulminant disease had a more marked expansion of B cells that can secrete immunoglobulin G anti-HEV than patients with uncomplicated infection and control patients.. These findings suggest that less-marked antiviral cellular immune responses and heightened antiviral humoral responses are associated with a more severe disease during HEV infection.

Topics: Acute Disease; Adaptive Immunity; Adolescent; Adult; B-Lymphocytes; Case-Control Studies; CD4 Lymphocyte Count; CD4-Positive T-Lymphocytes; Cell Proliferation; Cells, Cultured; Enzyme-Linked Immunosorbent Assay; Female; Hepatitis Antibodies; Hepatitis E; Hepatitis E virus; Humans; Immunity, Cellular; Immunity, Humoral; Immunoglobulin G; Interferon-gamma; Ionomycin; Male; Middle Aged; Recombinant Proteins; Severity of Illness Index; Tetradecanoylphorbol Acetate; Tumor Necrosis Factor-alpha; Viral Proteins; Young Adult

Hepatitis E virus (HEV) causes acute viral hepatitis and is endemic in the developing world. Few data are available on cellular immune responses in HEV infection. Using flow cytometry, we studied the frequencies of peripheral blood CD4(+) /CD8(+) T cells secreting interferon (IFN)-gamma, tumor necrosis factor (TNF)-alpha, and interleukin (IL)-4 in 21 patients with acute hepatitis E and 18 healthy controls, after stimulation with the HEV capsid (ORF2) protein. Cytokine levels in serum specimens and culture supernatants of ORF2-stimulated peripheral blood mononuclear cells (PBMCs) were estimated in enzyme-linked immunosorbent assays. In addition, cytokine mRNA transcripts were measured in PBMCs by reverse transcription-polymerase chain reaction. In patients with acute hepatitis E, although the total CD4(+) population was expanded, the proportions of CD4(+)/CD69(+) and CD8(+) /CD69(+) cells producing IFN-gamma, TNF-alpha, and IL-4 in response to HEV ORF2 stimulation were unchanged. However, IFN-gamma levels in the supernatants and IFN-gamma mRNA transcripts in cells were elevated in ORF2-stimulated PBMCs in acute hepatitis E; levels of IL-2 or TNF-alpha were unchanged. Our findings suggest that CD4(+) IFN-gamma-secreting cells, which do not belong either to the helper T cell type 1 or type 2 phenotype, as is the case with natural killer T cells, may be involved in the pathogenesis of hepatitis E. Further, the limited immune reactivity we detected in peripheral blood cells may be related to the sequestration of immune events to the intrahepatic compartment, which is the major disease site.

Topics: Acute Disease; Cytokines; Female; Hepatitis E; Humans; Ionomycin; Male; RNA, Messenger; T-Lymphocytes; Tetradecanoylphorbol Acetate; Viral Proteins

It is unknown whether neutrophilic inflammations can be regulated by T cells. This question was analyzed by studying acute generalized exanthematous pustulosis (AGEP), which is a severe drug hypersensitivity resulting in intraepidermal or subcorneal sterile pustules. Recently, we found that drug-specific blood and skin T cells from AGEP patients secrete high levels of the potent neutrophil-attracting chemokine IL-8/CXCL8. In this study, we characterize the phenotype and function of CXCL8-producing T cells. Supernatants from CXCL8(+) T cells were strongly chemotactic for neutrophils, CXCR1, and CXCR2 transfectants, but not for transfectants expressing CXCR4, CX3CR1, human chemokine receptor, and RDC1. Neutralization experiments indicated that chemotaxis was mainly mediated by CXCL8, but not by granulocyte chemotactic protein-2/CXCL6, epithelial cell-derived neutrophil attractant-78/CXCL5, or growth-related oncogene-alpha,beta,gamma/CXCL1,2,3. Interestingly, approximately 2.5% of CD4(+) T cells in normal peripheral blood also produced CXCL8. In addition to CXCL8, AGEP T cells produced large amounts of the monocyte/neutrophil-activating cytokine GM-CSF, and the majority released IFN-gamma and the proinflammatory cytokine TNF-alpha. Furthermore, apoptosis in neutrophils treated with conditioned medium from CXCL8(+) T cells could be reduced by 40%. In lesional skin, CXCL8(+) T cells consistently expressed the chemokine receptor CCR6, suggesting a prominent role for CCR6 in early inflammatory T cell recruitment. Finally, our data suggest that CXCL8-producing T cells facilitate skin inflammation by orchestrating neutrophilic infiltration and ensuring neutrophil survival, which leads to sterile pustular eruptions found in AGEP patients. This mechanism may be relevant for other T cell-mediated diseases with a neutrophilic inflammation such as Behçet's disease and pustular psoriasis.

Topics: Acute Disease; Animals; B-Lymphocytes; CD4-Positive T-Lymphocytes; Cell Survival; Cells, Cultured; Chemokines, CXC; Chemotaxis, Leukocyte; Culture Media, Conditioned; CX3C Chemokine Receptor 1; Drug Eruptions; Exanthema; Humans; Intercellular Signaling Peptides and Proteins; Interferon-gamma; Interleukin-4; Ionomycin; Membrane Proteins; Mice; Neutrophils; Receptors, Chemokine; Receptors, CXCR; Receptors, CXCR4; Receptors, G-Protein-Coupled; Receptors, Interleukin-8A; Receptors, Interleukin-8B; Skin; Skin Diseases, Vesiculobullous; T-Lymphocyte Subsets; Tetradecanoylphorbol Acetate; Transfection; Tumor Necrosis Factor-alpha

New therapeutic approaches are needed to improve the cure rates in acute myeloid leukaemia (AML). The present study was designed to investigate whether: (1) cytotoxic lymphocytes could be expanded from AML patients in complete remission; (2) their signal transduction machinery was preserved; (3) these cells were capable of producing cytokines involved in the cytolytic process; and (4) these cells showed cytotoxic activity against allogeneic and autologous blasts. By co-culturing blood mononuclear cells with feeder cells, we obtained an average 5.3-fold increase in the total cell number and a 35-fold increase in natural killer (NK) cells. Expression of the zeta chain and of tyrosine kinases of the Src and Syk-ZAP families involved in the triggering of NK functions was analysed on expanded cells. The results demonstrated a signal transduction apparatus preserved and quantitatively similar to that of normal donors. After phorbol myristate acetate and ionomicin stimulation, the ability of expanded cells to produce interferon gamma and tumour necrosis factor alpha was documented. Patients' expanded cells showed a cytotoxic activity against target lines and allogeneic blasts which was similar to that of normal donors. Purification experiments indicated that the NK cell fraction was responsible for most of the lytic effect. More significantly, these cells also exerted a lytic effect against autologous blasts that could be further enhanced following incubation with low-dose interleukin 2. These findings document the possibility of expanding cytotoxic effectors with preserved signal transduction machinery and autologous killing capacity from AML patients in remission, and suggest a new potential immunotherapeutic strategy for the management of early disease recurrence or of residual disease.

Topics: Acute Disease; Adult; Aged; Cell Division; Coculture Techniques; Cytokines; Cytotoxicity Tests, Immunologic; Female; Humans; Immunotherapy; Interferon-gamma; Ionomycin; Ionophores; Killer Cells, Natural; Leukemia, Myeloid; Male; Middle Aged; Signal Transduction; T-Lymphocytes, Cytotoxic; Tetradecanoylphorbol Acetate; Tumor Necrosis Factor-alpha

The transient T cell anergy associated with acute infectious mononucleosis (IM) caused by the Epstein-Barr virus has been analysed in a sample of 14 IM children. Peripheral blood mononuclear cells (PBMC) obtained from IM patients showed a significant specific impairment in their proliferative response to both phytohaemagglutinin (PHA; P less than 0.05) and to an anti-CD3 MoAb (P less than 0.001), although both responses reached normal control levels by addition of a submitogenic dose of either phorbol myristate acetate (PMA) or recombinant IL-2 (rIL-2). In contrast, activation signals delivered through other surface molecules (CD2, CD28) or other transmembrane pathways (PMA plus a calcium ionophore) elicited normal or high proliferative responses in most IM PBMC. In a group of five patients tested, the synthesis of IL-2 by IM PBMC in the presence of PMA was impaired when PHA or anti-CD3 was used as stimulus, but it reached normal levels with anti-CD2 or ionophore. Lastly, PHA failed to induce IL-2 alpha receptor (IL-2R alpha) expression in IM PBMC from four tested patients, but the presence of PMA completely corrected this defect. Taken together, these results strongly suggest that the T cell anergy associated with acute IM is due to a T cell receptor (TCR)-specific impairment in the induction of genes involved in T cell proliferation (including those coding for IL-2 and IL-2R alpha) upon membrane signalling to otherwise normal T lymphocytes, since CD2, CD28 and certain transmembrane activation pathways are uncoupled from CD3 in these particular pathological conditions (and perhaps in most in vivo situations). This and other similar experimental approaches to transient secondary immunodeficiencies may help to unravel the physiopathological role of different surface molecules in T cell activation.

Topics: Acute Disease; Antibodies, Monoclonal; Antigens, CD; Child; Child, Preschool; Humans; Immunity, Cellular; Infant; Infectious Mononucleosis; Interleukin-2; Ionomycin; Lectins; Lymphocyte Activation; Phytohemagglutinins; Receptors, Interleukin-2; Recombinant Proteins; T-Lymphocytes; Tetradecanoylphorbol Acetate