Immunological studies on CS-1170, a new semisynthetic cephamycin antibiotic

The antigencity of CS-1170, a newly developed semi-synthetic cephamycin, and it's cross-reactivity with beta-lactam antibiotics were studied. The antigencity was confirmed by the following tests: 1)the passive hemagglutination test with anti-CS-1170 antisera of guinea pigs immunized with CS-1170 plus Freund complete adjuvant, 2)lymphocyte proliferation response in vitro stimulated with this drug in the guinea pigs, 3) the PCA test using mice immunized with CS-1170-protein conjugates. The antibody to CS-1170 appears to be directed to the acyl side chain because cyanomethylthioacetylglycine, an univalent acyl side chain of the CS-1170, can significantly cross-react with the antibody. A methoxy group on the C-7 alpha-position of the antibiotic plays no important part for the antigenic specificity of the molecule. The cross-reactivity of CS-1170 with cefazolin, cephalothin, benzylpenicillin and ampicillin was only to a minimal extent in the passive hemagglutination test. The cross-reactivity of CS-1170 and the related antibiotics was not observed among them in the PCA system with IgE anti-CS-1170. These findings support a conclusion that CS-1170 is one of beta-lactam antibiotic with an immunologically minimal cross-reactivity to the related antibiotics.