STUDIES ON THE IMMUNOLOGICAL MECHANISMS OF PENICILLIN ALLERGY. II. ANTIGENIC SPECIFICITIES OF ALLERGIC WHEAL-AND-FLARE SKIN RESPONSES IN PATIENTS WITH HISTORIES OF PENICILLIN ALLERGY.

Forty-one patients with acceptable past histories of allergic reactions to benzylpenicillin (PG), eleven patients with questionable histories to PG and thirty patients without past histories of allergic reactions to PG were skin tested with various multivalent haptenic conjugates and with simple chemicals derived from PG in order to determine the antigenic specificities of penicillin hypersensitivity of the wheal-and-flare type. The benzylpenicilloyl (BPO) group was found to be the major haptenic determinant of wheal-and-flare type PG hypersensitivity. Twenty-nine per cent of patients with acceptable histories of PG allergy and 3 per cent of patients without histories of PG allergy gave positive wheal-and-flare reactions to multivalent BPO-conjugates. Three patients who had unusual clinical forms of PG allergic reactions demonstrated patterns of wheal-and-flare reactivity indicating D-penicillamine or D-benzylpenamaldic acid disulphide haptenic specificity. No unequivocal wheal-and-flare reactivity specific for the benzylpenicillenic acid haptenic group was observed in this study. Data were obtained which indicate that BPO-specific wheal-and-flare skin reactivity demonstrates specificity for the entire large BPO haptenic group, and also for structural areas of the immunizing autologous hapten-carrier protein (i.e. carrier specificity).