Immunoreactive neuropeptides in the cells of human thymus

The study was designed to explore the expression of different neuropeptides, viz. vasoactive intestinal peptide (VIP), calcitonin gene related peptide (CGRP), substance P (SP), bombesin and motilin in the cells of fetal and adult human thymus. Immunohistochemical staining revealed that cortical and medullary thymocytes were labeled by all antibodies, except those specific for motilin. Immunoreactive VIP and SP were observed in the solitary epithelial cells located in the subcapsular/subtrabecular cortex, at the corticomedullary junction and in the medulla. The cells within the subcapsular/subtrabecular monolayer, rare solitary cells in the deep cortex and epithelial cell network in the medulla, were labeled with antibodies to CGRP and bombesin. Hassall’s corpuscles were labeled with all antibodies except that specific for SP. The obtained data obtained testify to the expression of different neuropeptides in human thymic lymphoid and non-lymphoid cells and suggest a role for neuroendocrine hormone-mediated mechanisms in the regulation of thymic homeostasis in humans.