Major histocompatibility complex class II antigen (HLA-DR, DQ and DP) expression in human fetal skin.

Monoclonal antibodies were used to analyse skin samples from human fetuses (15-19 weeks gestational age) for the presence of class II major histocompatibility antigens (HLA-DR, DQ and DP). Cells expressing these antigens were clearly demonstrated within the epidermis from a proportion (4/7) of cases and were completely absent from the others. The negative samples were uniformly those with an epidermis of three cell layers or less. Such material may prove useful in studying the induction of class II antigen expression and the role of these antigens in allostimulation.