Immunohistochemical Study on Keratin Expression in Rat Hair Tissues Using Anti-Hair Keratin Monoclonal Antibodies

The study investigated keratin expressions in generating rat hair tissues using monoclonal antibodies HKN-2, 4, 5, and 6 on skin specimens from rats at various developmental stages. It was found that HKN-2 reacted with developing cells in several hair tissue components and epidermis, while HKN-4 showed broad reactivity with all skin epithelial cells, first appearing at the hair peg stage. HKN-5 and 6 were specific to hair tissues but did not react with the innermost cell layer of the outer root sheath or with hair tissue before anagen. The study concluded that hair germ differed from epidermal basal cells in keratin expressions, hair-specific keratins were produced after morphological differentiation, and the innermost cell layer of the outer root sheath may have distinct characteristics since hair generation.