title: Inhibition of HLA-DR antigen expression and of the allogeneic mixed leukocyte reaction by photochemical treatment.
abstract: Treatment of human peripheral blood mononuclear cells with UVB light, the photosensitizing system 8-methoxypsoralen plus UVA light (PUVA), or hematoporphyrin derivative plus visible light leads to an inhibition of their stimulatory capacity in an allogeneic mixed leukocyte reaction despite unaltered expression of HLA-DR antigens when tested immediately after irradiation. However, HLA-DR positive cells disappear among mononuclear cells in the interval between 4 and 8 h after treatment with either UVB, PUVA, hematoporphyrin derivative and light, or heating to 45 degrees C. The expression of HLA-DQ, but not HLA-A,B,C, antigens, was similarly affected by these treatments. The significance of these results is discussed.
mesh_terms: D000911:Antibodies, Monoclonal; D004307:Dose-Response Relationship, Radiation; D005455:Fluorescent Antibody Technique; D006680:HLA Antigens / Q000032:analysis; D015234:HLA-A Antigens; D015235:HLA-B Antigens; D015236:HLA-C Antigens; D006683:HLA-DQ Antigens; D006684:HLA-DR Antigens; D006414:Hematoporphyrin Photoradiation; D000949:Histocompatibility Antigens Class II / Q000032:analysis / Q000276:immunology / Q000528:radiation effects*; D006358:Hot Temperature; D006801:Humans; D008213:Lymphocyte Activation / Q000187:drug effects / Q000528:radiation effects*; D007959:Lymphocyte Culture Test, Mixed; D008214:Lymphocytes / Q000187:drug effects / Q000276:immunology / Q000528:radiation effects*; D008285:Major Histocompatibility Complex / Q000528:radiation effects; D011701:PUVA Therapy; D010778:Photochemotherapy; D013997:Time Factors; D014466:Ultraviolet Rays
chemical_list: D000911:Antibodies, Monoclonal; D006680:HLA Antigens; D015234:HLA-A Antigens; D015235:HLA-B Antigens; D015236:HLA-C Antigens; D006683:HLA-DQ Antigens; D006684:HLA-DR Antigens; D000949:Histocompatibility Antigens Class II