Distribution of major histocompatibility antigens in normal skin

The distribution of major histocompatibility antigens HLA-A,B,C (HLA), beta 2-microglobulin (beta 2m), and Ia-like antigens (HLA-DR; Ia) in normal skin was studied in frozen tissue sections by a four-step immunoperoxidase method and an avidin-biotin method employing monoclonal antibodies. HLA and beta 2m were present on the basal and spinous keratinocytes of the epidermis, on the outer root sheath epithelium in the infundibulum of the hair follicle, and on the excretory sebaceous duct epithelium. Ia-positive dendritic cells were found in the epidermis and hair follicles, but they were more frequent in the infundibulum and isthmus of the hair follicle than in its inferior portion or in the epidermis. In the straight eccrine duct, HLA and beta 2m-positivity was most striking in its lower portion. In the superficial duct, there was a less intense staining using the four-step procedure, but when an avidin-biotin method was used, the difference was less apparent. In contrast, the acrosyringial epithelium was markedly Ia-positive with decreasing intensity of staining as the duct penetrated the dermis. No HLA or Ia antigens were identified in eccrine glands and apocrine glands. Eccrine glands were slightly beta 2m-positive. HLA and beta 2m were uniformly present in non-dilated and dilated intradermal apocrine ducts.