[Immunologic tolerance to surface polysaccharides of serogroup A and C meningococci].

A single intravenous injection to mice of surface polysaccharides of meningococcal A and C serogroups in doses of 25--50 micrograms induces immunologic tolerance: the animals did not respond to the optimal dose (0.5 micrograms) of homologous antigens but were capable to form normal response to the heterologous polysaccharide Vi-antigen S. typhi. CBA mice were tolerant to polysaccharide A as long as 45 days, while noninbred ones were tolerant to the antigen only for 30 days. This pattern of tolerance did not prevent the formation of the immunologic memory. The animals who had lost tolerance were shown to be capable of forming the secondary response to another injection of antigen A.