Not all keratinocytes in human and rat hair follicles express MHC class I antigens (MHC I). In the present study, we report the first immunohistological profile of classical and non‐classical MHC I expression in the skin of adolescent C57 BL‐6 mice during the induced hair cycle. MHC I immunoreactivity (H‐2b, H‐2Db) is absent in the matrix and inner root sheath of growing (=anagen) hair follicles, and the dermal papillae are H‐2b negative during catagen and telogen. This lack of normal MHC I expression may serve to sequester potentially damaging autoantigens from immune recognition. In addition, we present the first evidence of non‐classical MHC class I antigen expression in normal mammalian skin: during the entire hair cycle, the distal hair follicle shows strong Qa‐2 immunoreactivity, which appears to be restricted to an epithelial follicle compartment densely populated by gamma‐delta T cells with which Qa‐2 molecules may interact as part of a primitive antibacterial defense system of the follicle. The murine hair cycle is an attractive model for dissecting the functional roles of H‐2b and Qa‐2 molecules in hair biology and in related tissue‐interaction systems.
|Original language||English (US)|
|Number of pages||7|
|Journal||British Journal of Dermatology|
|State||Published - Aug 1994|
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