Antitumour effects of streptococcal lipoteichoic acids on Meth A fibrosarcoma

The antitumour effects of lipoteichoic acids (LTA) extracted from Streptococcus pyogenes were studied in comparison with other streptococcal cellular components. LTA suppressed the tumour growth of both solid- and ascites-type Meth A fibrosarcoma as did the whole cells of S. pyogenes (OK-432). No other cellular components, such as cell wall peptidoglycan, group-specific C-carbohydrate or type-specific M protein, suppressed the growth of Meth A. LTA, but not the other cellular components, induced tumour necrosis factor (TNF) in Propionibacterium acnes-primed mice. LTA had no direct killing effects on Meth A cells. These results indicate that LTA may be an important antitumour component of OK-432 and that one of the antitumour mechanisms by this streptococcal preparation is the induction of TNF.