Differential Expression of the 4F2 Activation Antigen on Human Follicular Epithelium in Hair Cycle

Abstract

The expression of the 4F2 activation molecule has been studied on keratinocytes of human skin and hair follicle using immunoperoxidase staining with three different anti-4F2 monoclonal antibodies. Membranes of basal layer keratinocytes of the skin uniformly expressed this antigen, whereas a differential expression of this antigen was located in specific areas of the hair follicle. Follicles in the complete anagen phase displayed a strong 4F2 positive staining at the matrix and the outer root sheath cells. This positive staining gradually decreased along the proliferation zone, and became negative at the migration zone. Positivity was recovered in follicular cells at the duct of the sebaceous gland and was maintained in the upper outer root sheath where those cells fuse with the keratinocyte basal monolayer. Changes were also detected on different phases of the hair cycle. Follicles in the catagen-telogen phase expressed a very low number of positive cells in the matrix. Positive labeling progressively increased when the follicle was at the initial anagen stage, reaching a complete staining pattern in hair at the anagen phase. These results suggest that the expression of this activation antigen on hair keratinocytes may be related to the proliferation, active metabolism, and/or activation states of these cell types.