Localization of S100A2, S100A4, S100A6, S100A7, and S100P in the human hair follicle.

This study investigated the localization of S100 proteins in human hair follicles using specific monoclonal antibodies. S100A2 was strongly expressed in the outer-root sheath (ORS) and weakly in the cuticle and medulla. S100A6, S100A7, and S100P were found in the innermost cells of the ORS, while S100A4 was present in Langerhans cells and melanocytes. Sebaceous cells showed variable positivity for S100A2, S100A6, and S100A7, and a subset of dermal papilla cells expressed S100A4 and S100A6. The inner-root sheath was not labeled by any antibodies. The distinct distribution patterns of these proteins suggested their differential roles in the physiological functions of normal hair follicles.