Detection and characterization of polymers in cephalothin by passive cutaneous anaphylaxis in mice

Immunization of BALB/c mice by repeated injections of cephalothin (CET) - Ascaris suum extract conjugate resulted in formation of IgE antibodies, which were able to sensitize syngeneic animals for passive cutaneous anaphylaxis (PCA). By means of high-pressure liquid chromatography, a fraction with extremely high PCA-eliciting activity, but without appreciable antimicrobial activity, was isolated from the CET preparation. Physicochemical analyses of the fraction identified the major component of polymer impurities as being a proteinaceous complex with a molecular weight of 6,580. Very little cross-reactivity of CET and potassium benzyl penicillin (PcG) was noted when these antibiotics were used as the challenge antigens for PCA induced by corresponding murine antisera. The results of the inhibition studies indicated, however, that at least two antigens were involved in the PCA induced by anti-CET antibodies, one strictly specific for CET and another shared by PcG. Evidence was also presented that the nucleus structure and acyl side-chain structure of CET play the major role in the PCA elicited by the challenge with CET and its polymer, respectively.