Differential expression of major histocompatibility complex class II antigens on human keratinocytes

Skin biopsies from 136 patients with 30 different dermatoses and eight biopsies of normal skin were investigated with the avidin-biotin-peroxidase complex method with regard to the expression of major histocompatibility complex class II antigens human leukocyte antigen (HLA) HLA-DR, HLA-DQ, HLA-DP on keratinocytes. In normal skin the expression of these antigens was restricted to acrosyringia and Langerhans cells. In the dermatoses investigated HLA-DR was found in 51.5% (70 of 136), HLA-DQ in 24.3% (33 of 136), and HLA-DP in 20.5% (8 of 39). In 37 cases (27.2%) only HLA-DR could be detected, whereas in 33 cases (24.3%) HLA-DR was expressed jointly with HLA-DQ. Coexpression of HLA-DR and HLA-DQ was found especially often in cutaneous T cell lymphomas, skin tumors, and inflammatory dermatoses.