Immunosuppressive action of oral Streptococci

The study on the immunosuppressive activity of the cytoplasmic component (SF) from Streptococcus mitis on the immune response of mice to the sheep red blood cells (SRBC) was carried out. The bacterial cell suspension was disrupted in a Braun shaker. The disrupted cell suspension was diluted and centrifuged at 10,000 x g for 30 minutes to remove the cell walls. The supernatant was centrifuged at 31,000 x g for 45 minutes and the final supernatant was dialyzed against distilled water, frozen and lyophilized. These products were employed as the cytoplasmic component (SF). The SF in the extracts of Streptococcus mitis suppresses the antibody formation in mice against SRBC. It is effective to inject it just one day before the inoculation with SRBC.