OKT6 is not superior to HLA-DR or ATPase as a marker for Langerhans' cells in normal human epidermis

Interstitial dendritic cells

Interstitial dendritic cells (IDC) were first identified in the interstitium of non-lymphoid organs as leucocytes which stained intensely with anti-MHC class II antibodies. These cells have been identified in several species including man, and can be distinguished from tissue macrophages by their immunological phenotype and cytochemical and functional characteristics. IDC appear to be closely related to lymphoid dendritic cells (DC), and have the capacity to bind antigen and stimulate T lymphocyte responses. It seems probable that they represent a stage of nonlymphoid dendritic cell differentiation necessary for antigen surveillance, similar to the Langerhans cell of the skin. Exposure to antigen appears to induce migration of these cells into adjacent lymphatics and subsequent localization in the interfollicular areas of lymph node, where the DC present processed antigen to activate a primary T cell response. The IDC has been identified as the passenger leucocyte within organ allografts which contributes substantially to graft immunogenicity, so that eradication of donor organ IDC improves organ graft survival.

Occurrence of Langerhans cells and expression of class II antigens on keratinocytes in malignant and benign epithelial tumors of the skin: an immunohistopathologic study with monoclonal antibodies

We used an avidin-biotin complex immunoperoxidase technique with various monoclonal antibodies to determine Langerhans cell densities, class II antigen expression on keratinocytes, and phenotypes of other infiltrating cells in several malignant and benign epithelial tumors of the skin. Our observations indicate (1) there are few Langerhans cells in nests of basal cell carcinoma and squamous cell carcinoma; (2) there are increased Langerhans cell densities in seborrheic keratoses, verrucous epidermal nevus, and Bowen's disease; (3) there is an expression of class II molecules on the keratinocytes and cancer cells of basal cell carcinoma, squamous cell carcinoma, Bowen's disease, seborrheic keratosis, and verrucous epidermal nevus; and (4) there is a netlike staining of the keratinocyte surface with OKM5 in the epidermal lesion of seborrheic keratosis, verrucous epidermal nevus, and Bowen's disease, as well as in the epidermis adjacent to the basal cell carcinoma and squamous cell carcinoma nests.

Cellular kinetics of delayed hypersensitivity test reactions to topical glucocorticosteroids

The phenotypes of the infiltrating cells in 13 patients with delayed hypersensitivity to topical glucocorticosteroids (GCS) were studied from sequential biopsies of positive epicutaneous test reactions by using the avidin-biotin-complex (ABC) technique. Monoclonal antibodies were used to identify the cells with the following phenotypes: T3, T4/T4a, T6, T8, T9, T11, M1, Ia1 (HLA-DR), interleukin-2 receptor/T26a, and dendritic reticular cell. The cellular kinetics of GCS hypersensitivity reactions were compared with delayed hypersensitivity reactions caused by allergens not related to GCS. In both GCS and non-GCS reactions the epidermal dendritic T6+ cells were more numerous than dendritic Ia1+ cells. There was a decrease in the number of both cell types during these reactions; in GCS reactions the decrease in the number of T6+ cells was seen later than in non-GCS reactions. Ia1+ keratinocytes were seen at sites near dermal infiltrates. Compared with the non-GCS delayed hypersensitivity reaction, there were fewer pan T (T11+/T3+) in the GCS reaction. The relative numbers of M1+ monocytes and the T4/T8 ratio were substantially lower in the latter; these findings can be explained as a GCS effect which modulates the delayed type hypersensitivity reaction.

Dual expression of the cell-surface antigens HLA-DR and CD1 (T6) by Langerhans cells in human buccal mucosa and skin

The expression of HLA-DR and CD1 (T6) by Langerhans cells (LC) in human buccal mucosa and skin was investigated with the monoclonal antibodies YE2/36HLK (HLA-DR) and HTA1-C1 (CD1). A five-stage sequential double immunofluorescent-labelling technique, with rhodamine and fluorescein as the fluorochromes, was used to visualize the two surface antigens in the same microscope field. The majority of LC in cryostat sections of buccal mucosa and skin expressed both HLA-DR and CD1.