BINDING AND IN-VITRO MODULATION OF HUMAN EPIDERMAL LANGERHANS CELL FUNCTIONS BY SUBSTANCE-P

Substance P (SP) is distributed in both the central and peripheral ner vous system, It has various effects on immunocompetent cells, such as macrophages and lymphocytes. The aim of our study was to search for th e presence of SP receptors (SP-R) on human cutaneous Langerhans cells (LC), and to determine the effects of SP on LC immunological functions in a model of mixed epidermal cell-lymphocyte reaction (MELR), Radiol igand binding studies showed that LC-enriched epidermal cell suspensio ns reversibly bound SP, and that the specific binding increased with t he percentage of LC, Functional assays showed that SP had no effect wh en added at concentrations from 10(-6) M to 10(-12) M to the MELR. The addition of SP at concentrations of 10(-4) M and 10(-5) M was able to inhibit the allogeneic T-cell response (98.3 +/- 1.8% and 92.8 +/- 8. 9% inhibition, respectively) without modifying the cell viability, Thi s inhibition was through an effect of SP on both T-cell and LC functio n, We conclude that SP has receptors on LC and may inhibit antigen pre sentation.