[Normal antibodies and immunologic reactivity].

Antibodies to the capsular antigen of plague causative agent were found in the serum of many nonimmunized mice of 6 strains, but none were found in mice of the DBA/2 strain. After the administration of the capsular antigen to mice of different strains cells forming the antibodies to the antigen administered were revealed in a quantitative correlation with the natural antibody level. An association was revealed between the level of natural antibodies and the number of antibody-forming cells in the spleen of nonimmunized mice; it could be described by an equation almost all of whose members represented constant values with a definite quantitative characteristics. To check the suggested equation the concentration of immunoglobulins in the blood of mice was compared with the number of plasma cells in the spleen; a satisfactory correlation was revealed between them.