The Role of Penicillenic Acid and Penicillamine in Contact-Type Sensitivity to Penicillin

Abstract

Allergic contact sensitivity has been induced in guinea-pigs to benzyl penicillin, benzyl penicillenic acid and penicillamine by the repeated epicutaneous application of these substances dissolved in an organic solvent containing Tween 80. Cross-sensitivity reactions occurred between these three substances, and their pattern supported the concept that benzyl penicillin and benzyl penicillenic acid are `allergenically equivalent'. Seven patients with allergic contact dermatitis from penicillin were patch-tested with these substances; three showed cross-sensitivity to penicillamine and/or to benzyl penicillenic acid. The role of Tween 80 in the induction and elicitation of the animal sensitivity tests is briefly reviewed. The theory that benzyl penicillin sensitivity is determined by its unstable isomer, benzyl penicillenic acid, is outlined and it is suggested that the present experimental results support this theory.