Human skin cells synthesize HLA-DR molecules of the same charge and molecular weight as those synthesized by autologous lymphocytes.

Between 5 and 14% of human skin cells, separated by trypsinization, express HLA-DR antigen as detected by indirect immunofluorescence with monoclonal anti-DR antibody. To determine the source and structure of these DR molecules, skin cell suspensions were biosynthetically labeled with 35S-methionine and the radiolabeled DR molecules were analyzed by the method of two-dimensional polyacrylamide gel electrophoresis. The results indicated the presence of heavy, intermediate, and light chains indistinguishable from those of B lymphocyte DR. Gels in which DR immunoprecipitates from skin cells and autologous lymphocytes were run simultaneously confirmed this finding. Thus, skin cells and lymphocytes synthesize HLA-DR antigen of identical charge and molecular weight.