Cross-antigenicity between penams and cephems by intradermal skin test and leucocyte migration test in guinea pigs

The delayed-type hypersensitivity (DTH) reactions for penams or cephems of beta-lactam antibiotics were investigated by intradermal skin test and leucocyte migration test (LMT) in guinea pigs. The animals were immunized with ampicillin (ABPC) or cephalexin (CEX) using Freund's complete adjuvant. The cross-reactivities among ABPC, penicillin G (PCG) and cloxacillin as penam and CEX, cephalothin (CET) and cephalosporin C (CEPC) as cephem and phenylglycine (PhGly), which is the amino acyl side chain of ABPC and CEX, were examined. By intradermal reaction, ABPC-sensitized animals showed a cross-reaction with CEX, PCG and CET, but CEX-sensitized animals did not cause cross-reaction with ABPC. The CEX-sensitized group exhibited slight cross-reactions to CET and PhGly. PhGly exhibited low immunogenicity only in maximization test of guinea pig. The above results indicate that there is the difference in cross-reactivity between penams and cephems in skin test. In LMT, all the ABPC-sensitized animals reacted with ABPC and showed cross-reactions with all drugs tested. The CEX-sensitized group reacted with 4 out of 7 animals with CEX and exhibited cross-reactivities to ABPC, PCG, CET, CEPC and PhGly. The cross-reactivity between intradermal skin reaction and LMT elicited some different results.