Hair Cycle-associated Changes of the Immunological Markers in Human Hair Follicles / 대한피부과학회지

ABSTRACT

BACKGROUND: The immunological characteristics of human hair follicles with the hair growth cycle have not yet been fully elucidated. It is suggested that expressional changes of the immunological markers in the hair cycle may play a role in catagen induction of the hair follicles. OBJECTIVE: To analyze the immunological features in human hair follicles according to the hair growth cycle. METHODS: An immunohistochemical study was performed on frozen sections of human hair follicles using major histocompatibility complex (MHC) class I & II, CD1a, Fas, Fas ligand, and ACTH antibodies. We then compared the hair cycle-associated expressional changes of these markers. RESULTS: Human anagen hair bulbs showed very low level of the MHC class I expression. In catagen transition, enhanced expression of the MHC class I was observed in the proximal hair follicles. This change may correspond to regressing morphological change of hair follicles in the catagen transition. Some changes in the expression of MHC class II and Fas/FasL in hair follicles were also observed in catagen transition. CONCLUSION: Downregulation of MHC class I expression in the proximal epithelium of the anagen hair bulb may contribute to so-called 'immune privilege'. In catagen transition, the expression of MHC class II and Fas/FasL, together with upregulation of MHC class I, might be related to morphologic changes of the hair follicle.