Human IgG Antibodies to Carbohydrate and Protein Antigens in Mouse Protection Tests with Group B Streptococci

Summary: The protective effect of four commercial human gammaglobulin batches (I-IV) in mice was studied using six different strains of group B streptococci (GBS): types la; Ib; II, R-protein negative (R-); II, R+; III, R-; and III, R+. Each mouse received 1.0 ml gammaglobulin and 0.5 ml bacteria, 106-108 colony forming units (CFU). There was a close correlation between antibody levels measured by the use of radiolabeled protein A and the mouse-protective effect of the gamma-globulins. The mouse-protection tests demonstrated that batch I protected against GBS types la and III, R— at low concentration (65 mg/kg mouse weight), against type Ib at medium (260 mg/kg) and against type III, R+ at high concentration. Batch IV protected against types la and Ib, although the doses were four times higher than those in batch I, but did not protect against type III, R+. There was no mouse protection by any of the batches against type II.