MOLECULAR-FEATURES OF PENICILLIN ALLERGY

Haptens, such as drugs and other low molecular weight chemicals, becom e immunogenic only upon binding to proteins. Among antibiotics, penici llins are most commonly used for the treatment of bacterial infections and constitute a typical example of allergy inducing drugs in humans. Previous work on their immunologic properties focused mainly on the e xamination of IgE-mediated hypersensitivity reactions; however, drug-s pecific T cell reactions are also involved in causing a serious allerg ic inflammatory response. This review will focus on the interaction be tween antibiotic molecules and penicillin-specific T lymphocytes in hu mans. Experimental data accumulated so far on the reactivity of T cell s with penicillin G point to penicilloyl-modified, major histocompatib ility complex-associated peptides as T cell epitopes. The recognition specificity of the respective T cell receptors appears to be directed at both the backbone and the specific side chain of penicillin. In con trast, the sequence of the carrier peptides appears to contribute litt le to the antigenic specificity, mainly as a holder for the haptenic d eterminant. Finally, recent results demonstrating the capacity of peni cillins to modulate, in vitro, the Th0/Th2 phenotype of established T cell clones will be presented and discussed in relation to possible th erapeutic applications.