Immunocompetent cells of fixed drug eruption

Abstract

The positive provocation test reactions of the skin of six patients with fixed drug eruption (FDE) were studied from timed skin biopsies taken between 2 hours and 9 days after the appearance of FDE. Monoclonal antibodies to the following immunocompetent cell surface epitopes were used: T3, T4, T6, T8, T9, M1, Ia1, Drc, Leu7 and B cell. The dermal infiltrate comprised 60-80% of T lymphocytes at all the times studied. Cells with T4 and T8 epitopes were displayed in similar numbers. A transient decrease in the number of T6+ cells of the epidermis could be detected with a simultaneous and also transient increase of the T6+ cells in the dermis, which suggests a possible traffic of Langerhans' cells from the epidermis to the dermis. The epidermal Ia1+ cells showed changes similar to but less marked than the T6+ cells. The number of the dermal Ia1+ cells increased continuously. In the late biopsies these Ia1+ cells comprised up to 90% of the infiltrating cells. Except for the finding of a reduction of T6+ and Ia1+ epidermal cells, the cellular kinetics of FDE are similar to those seen in both cutaneous immunological and irritant reactions.