[Expression of class II HLA antigens (HLA-DR, DQW1, DQW3) in normal skin and cutaneous pathology].

We report the cutaneous expression of class II HLA antigens disclosed by immunohistochemical staining of normal and lesional skin with monoclonal antibodies (MoAbs) reacting with HLA-DR, DQW1 and DQW3 antigens. Briefly, we disclosed: on normal human skin: 1) The Langerhans cells (LC) HLA-DR+, DQW1+; 2) the acrosyringium HLA-DR+, DQW1+, DQW3+; 3) the dermal vessel endothelial cells HLA-DR+. On lesional skin: 1) The LC were found HLA-DQW3+ in the lesional skin of some cutaneous diseases; this expression was never shown on LC of normal human skin; 2) the epidermal keratinocytes disclosed an uniform membrane expression of HLA-DR antigens in some cutaneous diseases; this kind of expression was not found by immunostaining with MoAbs directed against HLA-DQ antigens; 3) in psoriatic lesions some keratinocytes disclosed an heterogeneous expression of HLA-DR, DQW1 and DQW3 antigens; 4) tumoral cells from cutaneous malignant melanomas were shown to be HLA-DR+, DQW1+, DQW3+. The HLA-DQW3 expression on the LC of lesional skin is in favour with a modulation of HLA-DQW3 expression by unknown factors present in pathological skin. The HLA-DR expression on epidermal keratinocytes suggests a functional collaboration of keratinocytes with LC in the genetic restriction of cutaneous immune reactions.