lipid-a and Neutropenia

B464 is a novel synthetic analog of lipid A, a toxic component of endotoxin (LPS; lipopolysaccharide). We investigated the effects of B464 on both LPS-induced cellular responses in vitro and acute lung injury in vivo. In the in vitro study, B464 inhibited tumor necrosis factor-alpha (TNF-alpha) production from human monocytes, priming and stiffening of neutrophils, and expression of adhesion molecules on endothelial cells induced by LPS. We then studied the effects of B464 pretreatment on acute lung injury elicited by intravenous LPS administration in vivo. Guinea pigs were divided into saline control, B464 alone, LPS alone, and LPS + B464 groups. Animals were observed for 4 h after LPS administration, and lung injury was evaluated by extravascular lung water, 125I-albumin leakage in lung tissue, and lung neutrophil accumulation. In the LPS alone group, rapid and sustained peripheral neutropenia (p < 0.001 versus saline at 15 min and at 1, 2, and 4 h), an increased plasma TNF-alpha concentration (p < 0.005 at 1 h), and increases in lung injury parameters (p < 0.05) were observed. In the LPS + B464 group, no changes were observed in either plasma TNF-alpha or lung injury parameters. Transient peripheral neutropenia and subsequent rapid recovery (p > 0.05, p < 0.001, p < 0.01, and p > 0.05 at 15 min and 1, 2, and 4 h, respectively) were observed in the LPS + B464 group. These in vivo data, together with in vitro evidence of suppressed cellular responses, suggest that B464 (1) inhibits neutrophil accumulation in lung tissue, and (2) attenuates the development of acute lung injury by blocking the activation of neutrophils and mononuclear cells as well as the interaction between neutrophils and endothelial cells.

Topics: Animals; Cell Adhesion Molecules; Endothelium, Vascular; Endotoxins; Guinea Pigs; Humans; In Vitro Techniques; Leukocytes, Mononuclear; Lipid A; Lipopolysaccharides; Lung; Neutropenia; Neutrophil Activation; Neutrophils; Respiratory Distress Syndrome; Tumor Necrosis Factor-alpha

Protective effects of SDZ MRL 953, a monosaccharidic lipid A analog with a reduced toxicity, were investigated in models of experimental septic shock caused by injections of LPS, and inoculations of heat-killed or live bacteria. Female B6D2F1 mice were challenged with a combination of galactosamine (800 mg/kg) plus various doses of heat-killed isolates of Escherichia coli, Pseudomonas aeruginosa, Salmonella typhimurium, and Staphylococcus aureus or LPS from Salmonella abortus equi. In some experiments, isolates of living bacteria at sublethal inocula were also combined with galactosamine. More than 90% of the animals died within 24 hr when the challenge was performed either simultaneously with or up to 4 hr after an intraperitoneal administration of galactosamine. No death was observed when galactosamine was omitted or administered after the microbial or LPS challenge. Pretreatment of the animals with SDZ MRL 953 (1-10 mg/kg) rendered the animals resistant to the lethal effects of both bacterial and LPS challenge in a time- and dose-dependent manner. The levels of TNF-alpha in control mice rose to greater than 600 pg/ml 2 hr postbacterial or LPS challenge, but were below detection in animals pretreated with SDZ MRL 953. Protection against both the infection and the toxicity of heat-killed bacteria or LPS was also achieved when murine anti-TNF-alpha monoclonal antibody was administered prophylactically. Together, these data suggest that SDZ MRL 953 enhances the resistance of mice against the toxicity of heat-killed gram-negative bacteria and S. aureus, and attenuates host responses to living bacteria which may lead to irreversible shock and death.

Topics: Animals; Anti-Bacterial Agents; Bacteria; Bacterial Physiological Phenomena; Female; Galactosamine; Hot Temperature; Immune System; Lipid A; Lipopolysaccharides; Mice; Mice, Inbred C57BL; Mice, Inbred Strains; Neutropenia; Shock, Septic; Survival Analysis; Tumor Necrosis Factor-alpha; Vaccines, Inactivated

Antibodies were raised in rabbits by immunization with the heat-killed J5 mutant of Escherichia coli O111 (Rc chemotype). Serum antibodies were separated into purified IgG and IgM by sequential affinity chromatography on protein G-Sepharose and anti-rabbit IgG-Sepharose columns. J5 lipopolysaccharide (LPS)-specific IgG was prepared by affinity chromatography of purified IgG on a J5 LPS-EAH Sepharose 4B affinity column. Purified IgM, IgG, and J5 LPS-specific IgG protected neutropenic rats against lethal challenge with Pseudomonas aeruginosa 12:4:4 (Fisher Devlin immunotype 6). Nine of 16 rats treated with the IgM fraction were protected (P < .001). Thirteen of 20 rats treated with the purified IgG and 6 of 8 treated with J5 LPS-specific IgG were protected compared with none of 25 treated with IgG made from the preimmune serum of the same rabbit (P < .001). These results demonstrate that purified J5 LPS-specific IgG protects against the lethal consequences of gram-negative bacteremia.

Topics: Animals; Antibody Specificity; Bacteremia; Bacterial Vaccines; Blotting, Western; Chromatography, Affinity; Enzyme-Linked Immunosorbent Assay; Escherichia coli; Female; Immunodiffusion; Immunoglobulin G; Lipid A; Lipopolysaccharides; Neutropenia; Pseudomonas aeruginosa; Pseudomonas Infections; Rabbits; Rats; Rats, Sprague-Dawley

We carried out a study in patients with severe neutropenia from hematologic malignancy and suspected gram-negative sepsis to evaluate the clinical significance of endotoxin concentrations in plasma before and during a therapeutic intervention with a human polyclonal immunoglobulin M (IgM)-enriched immunoglobulin preparation (Pentaglobin; Biotest, Dreieich, Germany). Twenty-one patients with acute leukemia or non-Hodgkin's lymphoma entered the study upon the development of clinical signs of gram-negative sepsis and received the IgM-enriched immunoglobulin preparation every 6 h for 3 days (total dose, 1.3 liter with 7.8 g of IgM, 7.8 g of IgA, and 49.4 g of IgG), in addition to standardized antibiotic treatment. Concentrations of endotoxin and IgM and IgG antibodies against lipid A and Re lipopolysaccharide (LPS) in plasma were determined by a modified chromogenic Limulus amebocyte lysate test and semiquantitative enzyme linked immunosorbent assay, respectively, before each immunoglobulin infusion and during the following 25 days. Seventeen patients were endotoxin positive; in five of these patients, gram-negative infection was confirmed by microbiologic findings. Prior to therapy, endotoxemia correlated significantly with the occurrence of fever, and a quantitative correlation between the endotoxin concentration and body temperature was found during the individual course of infection in 8 of the 17 patients. Overall mortality from endotoxin-positive sepsis was 41% (7 of 17) and 64% (7 of 11) in patients with symptoms of septic shock. Nonsurvivors had significantly higher maximum concentration of endotoxin in plasma compared with those of survivors at the first study day (median of 126 versus 34 pg/ml; P < 0.05) and during the whole septic episode (median of 126 versus 61 pg/ml; P < 0.05). In survivors, immunoglobulin therapy resulted in a significant decrease in endotoxin levels in plasma within the initial 18-h treatment period, from a pretreatment median value of 28 pg/ml to a value of 8 pg/ml (P< 0.05). In the seven patients who died from uncontrollable infection, no effect of therapy on endotoxin levels in plasma was observed. IgM and IgG antibodies against lipid A and Re LPS increased significantly under immunoglobulin treatment, with significant correlations between antibodies against lipid A and Re LPS. These data strongly suggest a prognostic significance of the endotoxin levels in plasma and a potential effect of treatment with a polyclonal IgM-en

Topics: Adult; Aged; Antibodies, Anti-Idiotypic; Endotoxins; Enzyme-Linked Immunosorbent Assay; Female; Gram-Negative Bacterial Infections; Humans; Immunoglobulin A; Immunoglobulin M; Kinetics; Lipid A; Male; Middle Aged; Neutropenia

Myelin basic protein, isolated from central nervous system tissue and an inducer of experimental allergic encephalomyelitis in animals, has been demonstrated to form a stable molecular complex with the lipid A region of gram-negative bacterial lipopolysaccharides (endotoxins). This binding of endotoxin with myelin basic protein results in generation of lower m.w. aggregates with decreased isopycnic density. A number of lipid A-induced characteristic properties of endotoxin, such as B lymphocyte proliferative response in C3H/St mice, complement activation of normal human serum, Limulus lysate gelation, and lethal effects in mice, are modified as a result of binding of myelin basic protein with lipopolysaccharides.

Topics: Animals; B-Lymphocytes; Binding Sites; Centrifugation, Isopycnic; Chromatography, Gel; Complement Activation; Female; Humans; Lipid A; Lipopolysaccharides; Lymphocyte Activation; Male; Mice; Mice, Inbred C57BL; Mortality; Myelin Basic Protein; Neutropenia; Rabbits

Topics: Animals; Endotoxins; Escherichia coli; Female; Humans; Lipid A; Lysosomes; Male; Neutropenia; Neutrophils; Rabbits; Salmonella; Superoxides