In situ localization of HuHF serine protease mRNA and cytotoxic cell-associated antigens in human dermatoses. A novel method for the detection of cytotoxic cells in human tissues.

Human Hanukah Factor (HuHF) is a trypsinlike serine protease associated with cytotoxic T lymphocytes (CTLs) and natural killer (NK) cells. Employing a radiolabeled RNA probe for the HuHF gene, cells containing HuHF mRNA in situ were detected in skin lesions from patients with a variety of reactive and neoplastic dermatoses including positive allergic contact dermatitis patch tests, lichen planus, erythrodermic psoriasis, Sezary syndrome, and poikilodermatous mycosis fungoides. The results were correlated with in situ studies of CTL/NK subsets as defined immunohistologically by a panel of monoclonal antibodies applied to sermiserial sections of the same tissue blocks used for the HuHF hybridizations. The results suggest that cytotoxic cells are present in each of these dermatoses, that they may be situated within either the epidermis or the dermis, and that they belong predominantly to the CTL subset because Leu-7+ or CD16+ cells (NK cells) were typically rare or absent. A variable proportion of cells expressed Leu-19 antigen (a marker for non-MHC-restricted cytotoxic cells); however, its rarity in several cases suggests that most of the HuHF+ cells identified in them belonged to the MHC-restricted, Leu-19- CTL subset. It is concluded that the correlation of molecular biologic and immunohistologic data will be a useful method for the further characterization of cytotoxic cell subsets in human dermatoses.