In situ identification of T6-positive cells in normal human dermis by immunoelectron microscopy*

Abstract

Monoclonal anti-T6 antibody, which reacts with the majority of cortical thymocytes but not peripheral T cells, also reacts with human epidermal Langerhans cells, as shown by a four-step immunoperoxidase method and immunoelectron microscopy. To define whether T6-positive cells are also present in normal human dermis, we used these techniques to demonstrate two immunologically distinct populations of histiocyte-like cells in normal human dermis. The first population contains cells devoid of phagolysosomes or Birbeck granules. These cells react with anti-T6 antibody, but not with monoclonal anti-T3 antibody which defines peripheral T cells, and are found predominantly in and around dermal lymphatic vessels. The second is composed of phagolysosome-containing cells which do not react with anti-T6 antibody or anti-T3 antibody. Because to date, Langerhans cells are the only cells in normal human epidermis that react with anti-T6 antibody, these data provide immunological evidence for a specific link between Langerhans cells and a T6-positive dermal mononuclear cell, possibly the so-called indeterminate cell. In addition, application of these techniques should, for the first time, permit the immunological distinction of these T6-positive mononuclear cells from other cells bearing Ia antigens, such as dermal histiocytes and certain lymphocytes, in normal and diseased skin.

Turnover and kinetics of epidermal langerhans cells and their dendritic precursor cells in experimental contact dermatitis

“…The Birbeck granule-negative IDCs are MHC class IIpositive epidermal cells which express the same immunological and cytochemical markers as non-activated LCs, and are therefore considered to be a subset of immature LCs [26,28]. The stimuli necessary for the occurrence of these distinct dendritic cells are not known.…”

“…It has become evident that this and other phenotypic markers of normal LCs change under various conditions, including antigen presentation [1,3,29,33], and therefore do not represent reliable markers for the identification and enumeration of pathologically altered epidermal LCs. Moreover, the indeterminate dendritic cells (IDCs) of the epidermis, which probably represent immature precursors of the LCs [26,28] bear the same markers as normal LCs and can therefore not be distinguished by immunohistological and histochemical staining methods.…”

Quantitative evaluation of two distinct cell populations expressing HLA-DR antigens in normal human epidermis

“…The panning method as previously reported by Reinherz et al (1981), Scheynius et al, (1982), Wysocki and Sato (1978) and ourselves (Czernielewski et al, 1983) was used, although it gave only moderate enrichment. Since its first report (Page-Faulk & Taylor, 1971), the immunogold labelling method has been largely used for the identification of cell surface antigens on cell suspensions by immunoelectron microscopy (De Mey, 1983;Horisberger, 1979;Lafferty el al., 1981) including quantitative evaluationsof labelling densities ofvarious cell surface markers (Laffertyi^r a/., 1981). Various advantages of this method can be noted: the absence of non-specific absorption of gold particles on cell surfaces, the possibility of post-staining ultrathin sections without changes in the immunolabelling contrast and of a double labelling using gold particles of different sizes.…”

“…Perhaps the indeterminate cells with a high density of HLA-DR antigens may represent activated and immature states of LC or functionally distinct subtypes. The T^ antigen is now considered as a highly specific differentiation marker of LC (Chu et al, 1982;Harrist ei al, 1983;Holden, Morgan & MacDonald, 1982;Murphy et al, 1982Murphy et al, , 1983. Monoclonal anti-Te antibody also reacts with dermal indeterminate cells (Murphy ei al, 1983).…”

Human cutaneous leishmaniasis: ultrastructural interactions between the inflammatory cells and leishman bodies in the skin lesions

“…These authors have also added that extracellular parasites appeared to enhance, both the activation and lytic processes, but degradation of these parasites were associated with dendritic-like cells (DLCs) more than with macrophages. In the present study, typical epidermal Langerhans cells (LCs), which may be related to DLCs, (Chu et al, 1982;Murphy et al, 1983), have been demonstrated in association to type II epithelioid cells. Our observations are also similar to those described for Trypanosoma cruzi (Kress et al, 1975;Noguiera & Cohn, 1976), which tend to escape from the FY to lie free in the host cell cytoplasm.…”