INCREASED ADHERENCE TO KERATINOCYTES OF PERIPHERAL-BLOOD MONONUCLEAR LEUKOCYTES OF A PATIENT WITH DRUG-INDUCED ERYTHEMA MULTIFORME

The pathogenetic mechanisms involved in the development of drug-induce d erythema multiforme (EM) are still largely unknown. The observation that epidermal keratinocytes (KC) in EM express intercellular adhesion molecule-1 (ICAM-1) points to a putative role for T-cell/KC adhesion in the pathogenesis of EM. In this study, the binding of peripheral bl ood mononuclear leucocytes (PBML) from a patient with carbamazepine-in duced EM and of normal control PBML to autologous and heterologous KC was investigated, using two different binding assays. Patient PBML obt ained at the time of disease (t0) showed an increased binding to ICAM- 1-positive heterologous KC, which could be inhibited completely by ant i-LFA-1. Adhesion of patient PBML-t0 to autologous KC, and to carbamaz epine-pretreated heterologous KC in sections of skin biopsies, was als o increased, but was found to be only partially LFA-1-dependent. These findings support the view that PBML/KC adherence plays an important r ole in the pathogenesis of this drug-induced EM.