The production of antibodies by young rats

Abstract

Suckling rats can produce specific agglutinins to Salmonella pullorum during the period when normally γ-globulin is being absorbed from the milk. This production of antibody is as efficient in rats prevented from suckling their mothers as it is in litter-mates suckling normally. The titres of young rats passively immunized by suckling mothers hyperimmune to Salm. pullorum show a decline between 18 and 24 days of age paralleling the decline of more than 80% in the concentration of serum γ-globulin which is known to take place over this period. Yet the titres of actively immunized young rats rise over the same period. These results suggest that the antibody produced by the active immunization is concentrated in the β-globulin, since this alone shows a marked rise during the period. It is known that the antibody activity in adult rats hyperimmunized against Salm. pullorum is concentrated in the γ-globulin. The results of the examination of electrophoretically separated protein fractions of the sera from actively immunized 24-day-old rats support this conclusion, as the bulk of the antibody was found to be present in those fractions which contained β-globulin. Evidence of the production of γ-globulin by the suckling rat was also obtained, however, because of the presence of a small but significant amount of antibody in a fraction containing only γ-globulin.