Expression of gastrin-releasing peptide receptor in human skin

Bombesin-related peptides are expressed in the skin of batrachians and mammals. As gastrin-releasing peptide belongs to this family, we searched for the presence and distribution of gastrin-releasing peptide receptors (GRPr) in the skin of healthy human adults by immunohistochemistry, flow cytometry and electron microscopy. The results indicated that GRPr are expressed on nerves and vessels in the dermis, on eccrine sweat glands, sebaceous glands and erector pili muscle. Within epidermis, staining was localized only on basal and suprabasal layer cells, or in the whole epidermis, according to the samples studied. Interestingly, suprabasal epidermal dendritic cells occasionally showed a strong labelling. Some of these epidermal dendritic cells were identified as Langerhans' cells by immunoelectron microscopy studies. Flow cytometry analysis of crude epidermal cell suspensions resulted in the expression of GRPr on about 43% of the cells. Therefore, we investigated whether human GRPr could modulate Langerhans' cells antigen-presenting functions. For this purpose, we added increasing concentrations of GRP (10(-12) to 10(-5) M) to mixed epidermal cell lymphocyte reactions. Allogeneic T-cell proliferation was not significantly modified when added to GRP-pretreated epidermal cells. In conclusion, we demonstrated the presence of GRPr in human skin, suggesting that GRP may modulate epidermal cell functions but does not modify antigenic presentation.