Important note: Information in this article was accurate in 2000. The state of the art may have changed since the publication date.
The human hair follicle immune system: cellular composition and immune privilege.
Br J Dermatol. 2000 May;142(5):862-73. Unique Identifier : AIDSLINE MED/20269809 Christoph T; Muller-Rover S; Audring H; Tobin DJ; Hermes B; Cotsarelis G; Ruckert R; Paus R; Department of Dermatology, University Hospital Eppendorf,; University of Hamburg, Martinistrasse 52, D-20246 Hamburg,; Germany.
Abstract:
The immunology of the hair follicle, its relationship with the 'skin immune system' and its role in hair diseases remain biologically intriguing and clinically important. In this study, we analysed the immunoreactivity patterns of 15 immunodermatological markers to determine the cellular composition and immune privilege of the human hair follicle immune system in anagen VI (growth phase). The most prominent cells located in or around the hair follicle were Langerhans cells, CD4+ or CD8+ T cells, macrophages and mast cells, whereas B cells, natural killer cells and gammadelta T cells were found very rarely. Langerhans cells (CD1a+, major histocompatibility complex, MHC class II+), and T cells (CD4+ or CD8+) were predominantly distributed in the distal hair follicle epithelium, whereas macrophages (CD68+, MHC class II+) and mast cells (Giemsa+) were located in the perifollicular connective tissue sheath. Transmission electron microscopy confirmed low numbers of immune cells in the proximal hair follicle epithelium, and very few macrophages and Langerhans cells were seen in the dermal papilla. Melanophages were observed in the connective tissue sheath and dermal papilla. MHC class I (HLA-A, -B, -C) and beta2-microglobulin immunoreactivity was found on most skin cells, but was substantially reduced on isthmus keratinocytes and virtually absent in the proximal hair follicle epithelium. Apart from the absence of Fas ligand immunoreactivity, the sharply reduced numbers of T cells and Langerhans cells, and the virtual absence of MHC class I expression all suggest that the anagen proximal hair follicle constitutes an area of immune privilege within the hair follicle immune system, whose collapse may be crucial for the pathogenesis of alopecia areata.
Keywords: JOURNAL ARTICLE beta 2-Microglobulin/BIOSYNTHESIS Adolescence Adult Aged Aged, 80 and over Antigens, CD20/ANALYSIS Antigens, CD95/BIOSYNTHESIS B-Lymphocytes/IMMUNOLOGY Biological Markers/ANALYSIS CD4-Positive T-Lymphocytes/IMMUNOLOGY CD8-Positive T-Lymphocytes/IMMUNOLOGY Hair Follicle/CYTOLOGY/*IMMUNOLOGY Histocompatibility Antigens Class I/IMMUNOLOGY Human Immunity, Cellular/*PHYSIOLOGY Intercellular Adhesion Molecule-1/ANALYSIS Keratinocytes/CHEMISTRY Killer Cells, Natural/IMMUNOLOGY Langerhans Cells/IMMUNOLOGY Macrophages/IMMUNOLOGY Major Histocompatibility Complex/IMMUNOLOGY Mast Cells/IMMUNOLOGY Middle Age Receptors, Antigen, T-Cell, gamma-delta/ANALYSIS Sebaceous Glands/IMMUNOLOGY Skin/IMMUNOLOGY Support, Non-U.S. Gov't T-Lymphocytes/CHEMISTRY
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Important note: Information in this article was accurate in 2000. The state of the art may have changed since the publication date.
