Ber‐EP4 antigen is a marker for a cell population related to the secondary hair germ

Abstract

Ber-EP4 is an antibody to a cell membrane glycoprotein of unknown function. In the skin, Ber-EP4 immunoreactivity has been reported to be localized in structures composed of basaloid epithelial cells, i.e. fetal epithelial germ cells, basal cell carcinoma, and trichoepithelioma as well as eccrine or apocrine ducts. In this study, we further characterized the follicular expression of Ber-EP4 immunoreactivity at different stages of the hair cycle of human terminal hair follicles. In addition, to clarify the location of Ber-EP4(+) cells, we compared the Ber-EP4 immunoreactivity with the expression of keratin 15 and keratin 19. Positive staining by Ber-EP4 was found in the lower part of the epithelial strand of late catagen hair follicles, in the secondary hair germ of telogen hair follicles, and in the matrix of early anagen hair follicles but not in any parts of mature anagen hair follicles. In contrast, the follicular expression of keratin 15 detected by using LHK15 antibody was restricted to two distinct parts of anagen hair follicles, i.e. the outer root sheath above the hair bulb and that of the isthmus including the bulge area, and to the outer root sheath of late catagen and telogen hair follicles. The follicular expressions of keratin 19 and that of keratin 15 were apparently superimposed, whereas keratin 15 expression was more extended. The immunoreactivity of LHK15 antibody and antikeratin 19 antibody against the secondary hair germ of telogen follicles was negative or dim. Our results suggest that Ber-EP4 reacts with the secondary hair germ and possibly a cell population related to the secondary hair germ but not with the presumptive stem cell population as revealed immunohistochemically either by the keratin 15 or keratin 19 expression.

Diverse phenotype of Brooke–Spiegler syndrome associated with a nonsense mutation in the CYLD tumor suppressor gene

“…Of the three characteristic adnexal tumours in this syndrome, controversy exists as to the origin of spiradenoma and cylindroma, and both apocrine and eccrine origins have been suggested. Immunohistological study using cell type‐specific markers, like the one done by Ozawa et al (19), could be helpful to discriminate distinct cell‐type origins of tumors in BSS.…”

Functional anatomy of the hair follicle: The Secondary Hair Germ

“…Thus, the SHG was brought back into relevance, especially in light of growing interest in HF stem cell kinetics. During recent years, a number of studies have been published addressing the role of SHG in anagen induction, in maintenance of the HF stem cell niche and in restoration of HF structure after its damage [eg]. Nevertheless, so far, there has been only one systemic attempt to elucidate the structural, functional and expressional nature of this cell population .…”

The immunohistochemical expression of CD34 in human hair follicles: a comparative study with the bulge marker CK15

“…In human hair follicles, the C8/144B antibody, originally raised against the carboxy‐terminal peptide of the T‐lymphocyte protein, CD8, delineates the bulge region in anagen, telogen and catagen follicles 6 . Likewise, in formalin‐fixed tissues, the LHK15 antibody, raised against a peptide derived from the last 17 amino acids of the CK15 polypeptide, delineates the isthmus area and a small segment of the outer root sheath located above the hair bulb 8 . However, when used in frozen sections, the antibody LHK15 appears to have a more extensive immunostaining pattern 7 …”