title: In-vitro stimulation of TNF-alpha from human whole blood by cell-free supernatants of gram-positive bacteria.
abstract: Gram-positive bacteria are being recognized increasingly as the cause of shock-like syndromes, clinically indistinguishable from those seen in association with Gram-negative endotoxic shock. Much clinical and experimental data link tumour necrosis factor-alpha (TNF-alpha) with the pathogenesis of endotoxic shock, and a number of studies of individual Gram-positive species have also implicated TNF-alpha. We report here the first systematic study of the ability of cell-free supernatants of common Gram-positive bacteria to induce TNF-alpha from human peripheral blood monocytes in vitro. Almost all the 63 strains were able to induce TNF-alpha, although the levels were substantially lower than those obtained from supernatants of Gram-negative bacteria, used as controls. Streptococcus pneumoniae, S. pyogenes, viridans streptococci and coagulase-negative staphylococci were consistently more active than group B and D streptococci. TNF-alpha induction did not correlate with conventional markers of pathogenicity; amongst strains of Staphylococcus aureus, commensal and blood culture isolates did not induce significantly different amounts of TNF. We conclude that cell-free supernatants of most Gram-positive bacteria are capable of inducing TNF-alpha from human peripheral blood monocytes in vitro, but the significance of this finding remains to be determined.
authors.affiliation: Department of Infectious Diseases & Bacteriology, Royal Postgraduate Medical School, London.
authors.forename: K
authors.initials: K
authors.lastname: Bayston
authors.forename: M
authors.initials: M
authors.lastname: Tomlinson
authors.forename: J
authors.initials: J
authors.lastname: Cohen
mesh_terms: D001427:Bacterial Toxins / Q000494:pharmacology*; D001773:Blood Cells / Q000378:metabolism*; D006094:Gram-Positive Bacteria / Q000276:immunology / Q000472:pathogenicity*; D006801:Humans; D066298:In Vitro Techniques; D008070:Lipopolysaccharides / Q000276:immunology; D012772:Shock, Septic / Q000503:physiopathology; D014409:Tumor Necrosis Factor-alpha / Q000096:biosynthesis*
chemical_list: D001427:Bacterial Toxins; D008070:Lipopolysaccharides; D014409:Tumor Necrosis Factor-alpha