Subsets of keratinocytes and Langerhans' cells express epitopes associated with suppressor-inducer capabilities in resting normal human epidermis.
In recent years two cell populations with down-regulatory immune capabilities have been identified in murine epidermis. The present report demonstrates that even in human epidermis at least two populations of cells expressing suppressor-inducer phenotypes (i.e. CD45R-positive) exist, namely small subsets of keratinocytes and Langerhans' cells, respectively. Highly specific and sensitive 5-nm colloidal gold-immunoelectronmicroscopic techniques were carried out using anti-CD45R monoclonal antibodies, on freshly isolated crude epidermal cell suspensions, and 4000 cells were scrutinized in the electron microscope. Over 2% of the total epidermal cell population was CD45R+. Subpopulation analysis revealed that approximately 2% of keratinocytes and about 5% of the total Langerhans' cell population showed strong gold-plasma membrane staining, whilst the remaining epidermal cells were absolutely negative. Heterogeneity of staining together with this somehow surprising distribution of CD45R positivity on non-lymphoid epidermal cells was confirmed by the negative controls. These CD45R+ Langerhans' cells and keratinocytes are clearly candidates for the cells which have been functionally demonstrated as being capable of inducing down-regulation responsiveness in the human epidermis. However, functional investigations are needed to clarify the roles of the CD45R+ keratinocyte and Langerhans' cell subsets in the modulation of cutaneous immune responses.
Department of Dermatology, University of Parma, Italy.
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De Panfilis
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Manara
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Ferrari
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Torresani
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Rowden
D015703:Antigens, CD / Q000276:immunology; D000943:Antigens, Differentiation / Q000032:analysis; D000939:Epitopes / Q000032:analysis*; D006801:Humans; D015603:Keratinocytes / Q000276:immunology*; D007801:Langerhans Cells / Q000276:immunology*; D017493:Leukocyte Common Antigens; D006377:T-Lymphocytes, Helper-Inducer / Q000276:immunology*; D050378:T-Lymphocytes, Regulatory / Q000276:immunology*
D015703:Antigens, CD; D000943:Antigens, Differentiation; D000939:Epitopes; D017493:Leukocyte Common Antigens