[The effect of substances produced by a strain of Streptococcus sp. Thom-1606 on phagocytic activity].

Among the substances produced by Streptococcus sp. strain TOM-1606 two fractions having the opposite influence on the phagocytic activity of peritoneal macrophages of white mice were detected. The fraction corresponding to peptides with a molecular weight not exceeding 10 kD activated natural phagocytosis. As shown in our earlier works, this fraction also had the maximum antimicrobial activity. The fraction with a molecular weight of 70-100 kD inhibited natural phagocytosis, acting as an immunosuppressive agent.