Radioallergosorbent test with conjugates specific for 'minor' haptenic determinants in the diagnosis of IgE-mediated penicillin allergy in man.

Penicillamine-polylysine, benzylpenicillanyl-human serum albumin and ampicillin-polymers were coupled to CNBr-activated paper discs and used in addition to penicilloyl G and penicilloyl V discs in RAST investigations. Sera from sixty patients with case histories of penicillin allergy and with positive or negative skin tests to different penicillin determinants and from seventeen subjects with atopic diseases caused by allergens other than penicillin were tested. The penicilloyl-('major' determinant) specific RAST (Phadebas RAST Penicilloyl G and V) was positive in twenty out of twenty-four patients with positive skin tests to penicilloyl-polylysine, in eight out of twelve patients with sole skin reactivity to 'minor' determinants, and in five out of twenty-four patients with negative skin tests to all antigens used. The penicillamine-specific RAST was the only positive in vitro test in four patients with negative skin tests (two) or sole positive skin reactivity to 'minor' determinants (two), whereas benzylpenicillanyl and ampicillin-polymer discs added no more information than the penicilloyl structures in all patients tested. Antibodies specific to 'minor' determinants apparently show strong in vitro cross-reactivity with the penicilloyl determinant. It is, therefore, concluded that 'minor' determinant specific conjugates are of marginal importance for in vitro diagnosis of penicillin-allergic patients.