IgE antibodies produced in mice instrumental in analyses of antigenicity of cephalothin preparation.

IgE antibodies to a cephalothin preparation were produced in mice which had been immunized with cephalothin-Ascaris extract conjugate mixed with Al(OH)3 gel plus Bordetella pertussis. Mice which had been irradiated just before receiving the booster injection wtih the conjugate showed higher IgE antibody levels against the preparation in comparison with unirradiated mice. The specificities of IgE antibodies against the preparation were examined with an inhibition test of passive cutaneous anaphylactic (PCA) reaction. The intensity of the PCA reaction evoked by the cephalothin preparation in the rats was substantially or partially reduced by a pretreatment of the animals with an injection of a cephalothin preparation from another source or a cephaloridine preparation. Meanwhile, a prior injection of a cefazolin, a 7-aminocephalosporanic acid, a benzylpenicillin (PcG) preparation, or an aminobenzylpenicillin preparation into the animals showed only weak or no influence on the PCA reaction. These results suggest that the acyl side chain of cephalothin plays an important role as eliciting antigenic determinant in the PCA reaction. The difference in the antigenic specificity between the cephalothin and PcG preparation is also discussed.