Recombinant gamma interferon and in vivo induction of HLA-DR antigens

Recombinant human IFN-gamma, used for treatment of melanoma and renal carcinoma, was found to induce HLA-DR expression on human keratinocytes in vivo. HLA-DR antigens bound to keratinocytes of the basal and suprabasal layers of the epidermis were observed after intramuscular or intravenous injections of 0.5 mg/kg body weight IFN-gamma, 3 times a week. Keratinocyte-bound HLA-DR antigens were first observed at the beginning of the third or fourth week of treatment, but HLA-DQ and HLA-DP antigens were never detected on keratinocytes. The intracytoplasmic constant (gamma) chain of the class II molecules was also not detectable within the keratinocytes. Patients who received IFN-alpha 2 therapy, did not exhibit keratinocyte-bound HLA-DR antigens.