LIPOTEICHOIC ACID FROM VIRIDANS STREPTOCOCCI INDUCES THE PRODUCTION OF TUMOR-NECROSIS-FACTOR AND NITRIC-OXIDE BY MURINE MACROPHAGES

Bacterial endotoxin or lipopolysaccharide is the major proinflammatory component of gramnegative bacteria, but the components of gram-positi ve bacteria that trigger the inflammatory cascade are poorly understoo d. Lipoteichoic acid (LTA) purified from 2 strains of viridans strepto cocci induced the accumulation of tumor necrosis factor (TNF) mRNA and protein by the murine macrophage cell line RAW 264.7 in a dose- and t ime-dependent manner. Furthermore, in the presence of recombinant inte rferon-gamma, LTA from both strains of viridans streptococci provoked the accumulation of inducible nitric oxide (NO) synthase mRNA and the production of NO. Together these observations indicate that LTA can tr igger macrophage activation and the production of TNF and NO and sugge st that LTA may be an important determinant of the host inflammatory r esponse to gram-positive infection.