P1.3 IDENTIFICATION OF AN ANTIGEN SPECIFIC TO THE HAIR FOLLICLE

H. Oura, ¹ H. Iwanari, ^2,3 K. Yoshizato, ⁴ S. Arase ¹

¹ Dept. of Dermatology, School of Medicine, The University of Tokushima, Tokushima, Japan; ² Institution of Immunology, Co., Ltd., Tokyo, Japan; ³ Perseus Proteomics Inc., Tokyo, Japan; ⁴ Dept. of Biological Science, Graduate School of Science, Hiroshima University, Higashihiroshima, Japan

Objective and Methods: The human cutaneous epithelium includes three tissues, the interfollicular epidermis, the hair follicle epidermis, and nail epidermis. These tissues are composed of several epithelial compartments which show unique patterns of the tissue-specific differentiation. Their differentiation patterns are thought to be grouped into at least two types, the skin-type and the hair-type differentiation. To obtain a hair follicle specific marker, we yielded mouse monoclonal antibodies (mAbs) by immunizing with rat vibrissa follicles. In the present study a mAb dubbed K25070 was immunohistochemically characterized to examine the expression of its antigen in developing hair follicles in human fetal skin, ranging in age from 9 week to 24 week estimated gestational age (EGA) and in hair follicles of adult scalp.

Results and Conclusion: During the process of hair follicle morphogenesis, K25070 mAb reacted with the cytoplasm of matrical cells in the peg at the hair germ stage to the bulbous hair peg stage. In hair-producing fetal follicles, immunoreactive cells were located in the infundibulum, but not in the bulb area. In the anagen follicles of human adult scalp, this mAb reacted with outer root sheath cells from lower part of the infundibulum to upper part of the Isthmus, and this staining pattern was observed in the catagen and telogen follicles. These histological results suggest that the antigen for K25070 mAb may contribute to the morphogenesis of hair follicles in fetal skin and to the hair growth cycle in adult scalp. We are investigating to clarify the amino acid sequencing of an antigen reactive with K25070 mAb.