Cellular immunity to Bacteroides fragilis capsular polysaccharide.

Abstract

The polysaccharide capsule of B. fragilis is important in the virulence of the organism. The capsular polysaccharide (CP) of B. fragilis was extensively purified. Using a murine model of intraabdominal abscess formation, cellular immunity to the capsular polysaccharide of B. fragilis was demonstrated. Immunization of C57BL/10J mice with the CP for 5 wk prevents abscess formation when the mice are challenged with B. fragilis i.p. This immunity can be transferred to naive mice with spleen cells from immune animals. The immune cells bear Thy-1.2 and Ly-2.2. antigens. The immune response is antigen specific but not H-2 restricted. The possibility that these immune cells are suppressor T cells is discussed. The experimental system presented provides a model for the examination of the cellular interactions responsible for abscess formation and the cellular response to bacterial pathogens.