[Effect of Neisseria meningitidis on the humoral response of various strains of mice immunized with ram erythrocytes].

The capacity of heat-killed meningococci and the polysaccharide-protein-lipopolysaccharide fraction ( PPLF ) isolated from the microbial cell wall for changing nonspecific immunological reactivity was studied. In this investigation CBA mice with high response and C57BL/6 mice with low response to sheep red blood cells (SRBC) were used. Heat-killed N. meningitidis, serogroup A, and PPLF , serogroups A and B, were found to enhance and suppress humoral response to the heterologous antigen. The effect of modulation depended on the dose of the antigen, the serogroup of meningococci, the scheme of the experiment and the strain of mice. The immune response of the vaccinated animals to the heterologous antigen was characterized by the following stages: the state of the adjuvant effect was replaced by the state of temporary immunodeficiency and then by enhanced response to SRBC.