ROLES OF THE BACTERIAL-CELL WALL AND CAPSULE IN INDUCTION OF TUMOR-NECROSIS-FACTOR-ALPHA BY TYPE-III GROUP-B STREPTOCOCCI

Group B streptococci (GBS) are the major cause of sepsis and fatal sha ck in neonates in the United States, The precise role of tumor necrosi s factor alpha (TNF-alpha) in the development of human GBS sepsis has not been defined; however, whole GBS have been shown to induce the pro duction of this inflammatory cytokine. We sought to determine which ba cterial cell wall components of GBS are responsible for triggering TNF -alpha production, Human cord blood monocytes were stimulated with enc apsulated (COH1) or unencapsulated (COH1-13) whole type III GBS or wit h purified bacterial components, including type III capsular polysacch aride (III-PS), group B polysaccharide (GB-PS), lipoteichoic acid (LTA ), or peptidoglycan (PG), Lipopolysaccharide from Escherichia coli ser ved as a control, Supernatants were harvested at specific timed interv als, and TNF-alpha levels were measured by enzyme-linked immunosorbent assay. Monocytes exposed to COH1 and COH1-13 induced similar amounts of TNP-alpha, III-PS, GB-PS, LTA, and PG each induced TNF-alpha in a t ime- and concentration-dependent manner. However, TNF-alpha release wa s significantly greater after stimulation by the GB-PS or PG than afte r stimulation by III-PS or LTA (P < 0.05), Our findings indicate that GB-PS and PG are the bacterial cell wall components primarily evoking TNF-alpha release, These, alone or in concert with other factors, may be responsible for septic shock accompanying GBS sepsis.