Localization of S100A2, S100A4, S100A6, S100A7, and S100P in the Human Hair Follicle

The study investigated the localization of S100A2, S100A4, S100A6, S100A7, and S100P proteins in human hair follicles using specific monoclonal antibodies. S100A2 was strongly expressed throughout the outer-root sheath (ORS) and weakly in the cuticle and medulla of the bulb. S100A6, S100A7, and S100P were found in the innermost cells of the ORS, while S100A4 was present in dendritic Langerhans cells and melanocytes. Sebaceous cells showed variable immunopositivity for S100A2, S100A6, and S100A7, and a subset of dermal papilla cells expressed S100A4 and S100A6. The inner-root sheath did not show labeling with any antibodies. The distinct spatial distributions of these S100 proteins suggested their differential involvement in the physiological functions of normal hair follicles.