Immune response of rats to group A streptococcal vaccine.

Adult female Sprague-Dawley rats were hyperimmunized with group A streptococcal vaccine in an attempt to evaluate this species for its immunological responsiveness to the group A streptococcal carbohydrate. Pronounced hyperproteinemia, generally attributable to hypergammaglobulinemia was produced in 30 to 40% of the animals. The immune response of the rats was extremely variable, yielding precipitating antibody concentrations ranging from <0.1 mg per ml to >26 mg per ml. Antibody levels also varied considerably in the same rat at different times during the immunization routine. The highest concentration of precipitating antibody was 26.3 mg per ml. Evidence is presented to suggest the production of antibodies of restricted heterogeneity and the production of non-streptococcal antibodies during the immune response.