Clinical patterns and results of radioallergosorbent test (RAST) and skin tests in penicillin allergy

Abstract

Patients (79) with acute or former reactions to penicillin were investigated by a benzyl-penicilloyl (BPO)-specific RAST and/or by skin tests with penicilloul-polylysine (PPL), benzyl-penicillin and penicilloic acid, and the results were correlated with the different clinical pictures. Positive RAST and skin test results could be found in patients with anaphylactic shock, urticaria and serum sickness-like reaction, and sometimes in a special group of exanthems often observed after high-dosage penicillin therapy, and characterized by the existence of many different lesions at the same time, therefore called polymorphic exanthems. In cases of scarlatiniform or morbiliform exanthems no positive results were found. The BPO-specific RAST showed an overall correlation of 95.1% with skin tests using PPL. Some patients with positive skin tests to benzylpenicllin and penicilloic acid did not have detectable circulating IgE [immunoglobulin E] antibodies to BPO. This emphasizes the need for including these antigens in vitro methods. The RAST was informative at the time of the allergic reaction or in the first 15 days afterwards and seems to be very valuable for early diagnosis of penicillin allergy, especially in cases when many drugs have been given.