Effects of neuropeptides and hormones on Langerhans cells

Abstract

Significant evidence suggests that the nervous and immune systems have regulatory interactions within the skin. Langerhans cells (LCs) are dendritic antigen‐presenting cells that reside within the epidermis. By laser confocal scanning microscopy, LCs in human skin have been found to be frequently in anatomic association with epidermal nerves. Additionally, a minority of LCs have been found by immunohistochemistry to have the neuropeptide calcitonin gene‐related peptide (CGRP) on or near their cell surfaces. Functional studies have demonstrated that CGRP, pituitary adenylate cyclase‐activating polypeptide, and vasoactive intestinal peptide inhibit antigen presentation by LCs, at least in some assays. Epinephrine and norepinephrine also have been shown to inhibit LC antigen presentation in vitro. Some of these agents appear to exert their effects through regulation of the expression of cytokines and costimulatory molecules. Furthermore, some of these agents inhibit the acquisition of contact hypersensitivity after intradermal administration. As a whole, these findings suggest a regulatory locus of interaction between the immune system and the nervous system within the skin.