HLA-DR expression on keratinocytes is a common feature of diseased skin.
Biopsy specimens from 185 patients with 52 different skin disorders were investigated by indirect immunofluorescence staining for the presence of HLA-DR bearing keratinocytes and their association with an underlying inflammatory infiltrate and in particular with activated (HLA-DR-positive, Leu-4-positive) T lymphocytes. HLA-DR expression on keratinocytes was demonstrated in 38 dermatoses, including lymphocytic vasculitis, lupus erythematosus, morphea, vitiligo, lichen planus, cutaneous T-cell lymphoma, various infectious dermatoses, allergic contact dermatitis, granulomatous dermatoses, Sweet's syndrome, lichen sclerosus and erythema nodosum. In 27 of these this had not previously been reported. Occurrence of HLA-DR on keratinocytes was invariably linked to the presence of a lymphocytic infiltrate containing numerous activated T-cells (Leu-4 +, HLA-DR +) whereas such infiltrates were not accompanied by HLA-DR expression on keratinocytes in all the dermatoses investigated, as in pseudolymphoma and erythema anulare centrifugum. However, HLA-DR positive keratinocytes were consistently absent in skin disorders lacking any significant lymphocytic infiltration (e.g. leukocytoclastic vasculitis, bullous autoimmune dermatoses, genodermatoses and mastocytosis). Although it has been suggested that HLA-DR-positive keratinocytes are involved in various immune responses of the skin, their exact functional significance is, as yet, unknown.
Auböck
J
J
Romani
N
N
Grubauer
G
G
Fritsch
P
P
D004817:Epidermis / Q000473:pathology; D005455:Fluorescent Antibody Technique; D006684:HLA-DR Antigens; D000949:Histocompatibility Antigens Class II / Q000032:analysis*; D006801:Humans; D007633:Keratins; D008213:Lymphocyte Activation; D012867:Skin / Q000276:immunology*; D012871:Skin Diseases / Q000276:immunology* / Q000473:pathology; D013601:T-Lymphocytes / Q000276:immunology
D006684:HLA-DR Antigens; D000949:Histocompatibility Antigens Class II; D007633:Keratins