STUDIES ON RELATION OF A PRIOR IMMUNE RESPONSE TO IMMUNOGENICITY

Abstract

Two polymers of D-glutamic acid, one synthetic (poly-[alpha]-D-glutamic) and the other the capsular polypeptide of Bacillus anthracis (poly-gamma-D-glutamic), which did not induce detectable antibody when injected in saline, elicited precipitating antibody in rabbits when complexed with methylated bovine serum albumin [MBSA]. Animals that made an immune response to either of the polypeptides did not produce detectable anti-hapten antibodies when subsequently immunized with the homologous polypeptide conjugated with p-amino-p[image]-dimethylaminoazobenzene (PDA) groups. Neither was there an observable response to the polypeptide carrier. Hapten-specific antibody was elicited with an immunogenic carrier, hen egg albumin, and with the polypeptide-PDA conjugates complexed with MBSA, demonstrating that PDA could act as a determinant under the appropriate conditions. Rabbits that had made PDA-specific antibody were entirely refratory to polypeptide-PDA conjugate, inasmuch as their levels of anti-PDA antibody remained unchanged. The formation of antibody against a weakly immunogenic molecule may not alter the state of responsiveness of the animal upon subsequent contact with that molecule. Such a molecule cannot serve as a carrier for another structural determinant, in animals that have made a prior immune response to the carrier or to the determinant.