IN-VITRO QUANTIFICATION OF CROSS-REACTIVITY BETWEEN BETA-LACTAM ANTIBIOTICS AND ANTI-BENZYLPENICILLIN ANTIBODIES

The phenomenon of cross-reactivity between allergens and anti-antibodi es is believed to be a major factor underlying the incidence of immuno logically mediated adverse reactions. A sensitive reproducible competi tive enzyme-linked immunosorbent assay (ELISA) has been developed for the quantitative determination of the extent of cross-reactivity occur ring between native beta-lactam antibiotics and anti-benzylpenicillin serum antibodies (anti-BPAbs) raised in presensitized rabbit serum in which free native antibiotic at a concentration of 3 mM, and benzylpen icillin cytochrome c (BPCC) adsorbed onto a solid surface, compete to bind free anti-BPAbs. The extent of BPPC-anti-BPAb binding is determin ed spectrophotometrically, following the addition of enzyme-labelled a ntispecies antiglobulin and a suitable substrate. The assay has been u sed to determine the levels of cross-reactivity exhibited by 29 commer cially available beta-lactam antibiotics (14 penicillins and 15 cephal osporins), with results attained ranging for the penicillins between 9 .1 and 100% and for the cephalosporins from 0.0 to 19.9%. The results thus indicate that cross-reactivity between different beta-lactams and anti-BPAbs does occur in vitro and that different beta-lactams cross- react to different extents, with cephalosporins cross-reacting less th an the penicillins. Copyright (C) 1996 Elsevier Science Ltd