title: Spatial relationship between Merkel cells and Langerhans cells in human hair follicles.
abstract: The distributions of Merkel cells and Langerhans cells within human hair follicles have been reported. However, there has been no description of the relationship between Merkel cells and Langerhans cells, which were discovered by 19th century German pathologists. Merkel cells and Langerhans cells share some similar characteristics such as the localization of human hair follicles, a close association with peripheral nerves and the expression of several neuropeptides. Merkel cells were stained with CK20 or CAM5.2, while Langerhans cells were stained with CD1a or S-100 protein. We thus immunohistochemically confirmed the preferential localization of Merkel cells and Langerhans cells in normal human hair follicles. Using a double staining technique, two- and three-dimensional observations demonstrated that a small proportion of Merkel cells were closely contacted with Langerhans cells below the sebaceous gland level, presumably indicating the bulge area. Merkel cells and Langerhans cells connected directly or approached each dendrite within the basal layer of the outer root sheath. For the first time, we demonstrated a close anatomical relationship between Merkel cells and Langerhans cells within the bulge area of human hair follicles where follicular stem cells may be present. These morphological observations suggest a functional interaction between follicular Merkel cells and Langerhans cells. We herein hypothesize that Merkel cells communicate with Langerhans cells by characteristic dendrites in which some neuropeptides or cytokines may be stored.
authors.affiliation: Department of Internal Medicine, Saga Medical School, Nabeshima 5-1-1, Saga City 849-8501, Japan.
authors.forename: Kayo
authors.initials: K
authors.lastname: Taira
authors.forename: Yutaka
authors.initials: Y
authors.lastname: Narisawa
authors.forename: Jyunji
authors.initials: J
authors.lastname: Nakafusa
authors.forename: Noriyuki
authors.initials: N
authors.lastname: Misago
authors.forename: Tatsurou
authors.initials: T
authors.lastname: Tanaka
mesh_terms: D018859:Hair Follicle / Q000166:cytology*; D006801:Humans; D007124:Immunoenzyme Techniques; D007150:Immunohistochemistry / Q000379:methods; D007801:Langerhans Cells / Q000166:cytology*; D018862:Merkel Cells / Q000166:cytology*; D013194:Staining and Labeling