Ber-EP4 Antigen Is a Marker for a Cell Population Related to the Secondary Hair Germ

The study investigated the expression of Ber-EP4 antigen in human hair follicles at different stages of the hair cycle. Ber-EP4 was found to be positively stained in the lower part of the epithelial strand of late catagen hair follicles, the secondary hair germ of telogen hair follicles, and the matrix of early anagen hair follicles, but not in mature anagen hair follicles. This contrasted with keratin 15, which was expressed in specific parts of anagen, catagen, and telogen hair follicles, and keratin 19, which had overlapping expression with keratin 15. The findings suggested that Ber-EP4 is a marker for the secondary hair germ and possibly a related cell population, but not for the presumptive stem cell population indicated by keratin 15 or keratin 19.