IMMEDIATE HYPERSENSITIVITY TO PENICILLINS - STUDIES ON ITALIAN SUBJECTS

The IgE response, the involvement of the different penicillins availab le for therapeutic use, and the specificity of the IgE antibodies foun d in a group of penicillin-allergic subjects from Italy were studied. Thirty subjects with a history of allergic reactions to penicillins we re studied. In vivo and in vitro specific IgE antibodies were determin ed to different penicillin determinants. Fifteen subjects developed an aphylactic responses and the remainder urticaria and angioedema. The d rug most frequently involved in the patients' allergic reactions was a mpicillin (AMP). The benzylpenicilloyl (BPO) skin test was positive in 16 (53.3%) patients, whereas 23 (76.6%) patients were positive to min or determinant mixture (MDM), benzylpenicillin (PG), AMP, or amoxicill in (AX). When classified according to initial reaction type, most anap hylactic patients (93.3%) were associated with minor determinant react ivity, whereas most urticaria patients (80%) reacted to BPO. RAST resu lts for the anaphylactic and urticaria subgroups were similar. RAST in hibition showed that most sera contained highly cross-reactive IgE ant ibodies. There was evidence of a specific response to AX and PG (one p atient each). These data show that in a population of penicillin-aller gic patients from Italy, AMP was the main drug inducing the allergic r eaction. In skin tests and RAST, patients exhibited heterogeneous IgE responses with little indication of specific reactivity to AMP.