Characterization of LHTric-1, a new monospecific monoclonal antibody to the trichocyte keratin Ha1

Summary The hair follicle is a heterogeneous tissue involving differentiation of both hair forming (trichocyte) and non-hair forming (root sheath) cells; while there are many antibody markers available which can determine the distribution of ‘soft’ epithelial keratins, fewer have been described which are truly monospecific for hair specific ‘hard’ keratins. We employed the proven strategy of raising monoclonal antibodies to a short synthetic peptide from the carboxy-terminal sequence of mouse Ha1 and report here the successful production of a monospecific monoclonal antibody which we have called LHTric-1. We have characterized the antibody using immunostaining on rat and human tissues and by immunoblotting against an extract of human follicles. The antibody cross-reacted between rat and human tissue but did not stain formalin-fixed tissue. LHTric-1 localized very specifically to the pre-cortical region of the hair follicle in early anagen and to pre-cortical cells in the upper bulb in anagen. Telogen follicles did not react. LHTric-1 immunoreacted within tongue and nail, staining being restricted to the mid-line above the connective tissue core in tongue and to the suprabasal layers of the nail matrix. The antibody did not react with the fully keratinized hair or nail plate. Finally, in immunoblotting. LHTric-1 reacted with a single band of 44kDa, suggesting that a single protein was recognized. We conclude that this antibody, by virtue of its known antigen sequence specificity, will be useful in research into the formation of hair and nail in normal and diseased states.