Human keratinocytes express HLA-DR antigens in the tuberculin reaction.
The cellular response in the human skin tuberculin reaction was studied with immunohistochemical double-staining techniques in frozen sections of skin biopsies taken 6 h to 8 days after intradermal PPD injections. Cell infiltrates were observed from day 2 onwards and increased in size up to 4 days. Most of the infiltrating cells reacted with anti-Leu 3a (T 'helper/inducer' phenotype) antibodies. In contrast to normal epidermis, not only Langerhans cells but also keratinocytes expressed HLA-DR antigens from day 4 onwards. The induction of HLA-DR antigens on keratinocytes may be secondary to T-cell activation. Since the HLA-DR expression on keratinocytes appeared late in the tuberculin reaction, the function may be to suppress rather than enhance the immune response.
D000328:Adult; D000818:Animals; D000911:Antibodies, Monoclonal / Q000276:immunology; D004817:Epidermis / Q000276:immunology*; D005455:Fluorescent Antibody Technique; D006684:HLA-DR Antigens; D000949:Histocompatibility Antigens Class II / Q000032:analysis* / Q000276:immunology; D006801:Humans; D006968:Hypersensitivity, Delayed / Q000175:diagnosis / Q000276:immunology*; D007124:Immunoenzyme Techniques; D011817:Rabbits; D011947:Receptors, Antigen, B-Cell / Q000276:immunology; D013601:T-Lymphocytes / Q000145:classification; D014374:Tuberculin Test
D000911:Antibodies, Monoclonal; D006684:HLA-DR Antigens; D000949:Histocompatibility Antigens Class II; D011947:Receptors, Antigen, B-Cell