INTERLEUKIN-10 INHIBITS THE PRIMARY ALLOGENEIC T-CELL RESPONSE TO HUMAN EPIDERMAL LANGERHANS CELLS

In this study, we analyzed the effect of interleukin-10 (IL-10) on the primary allogeneic T cell response induced by human Langerhans cells (LC), the dendritic cells from epidermis. We showed that IL-10 strongl y inhibited the T cell response, provided it was added at the beginnin g of the mixed epidermal cell lymphocyte reaction (MELR). Proliferatio n of both CD4(+) and CD8(+) T cell subsets was affected by the cytokin e. An inhibitory effect of IL-10 on human LC allostimulatory function was evidenced by the fact that IL-10-preincubated LC, but not IL-10-pr eincubated T cells, can display inhibitory effect. LC treatment with I L-10 partially inhibited the increase of HLA-DR expression on cultured LC as the percentage of highly positive HLA-DR cells was lower than t hat observed in the absence of the cytokine. IL-10 inhibited T cell al loreaction induced by 2-day-cultured human LC which constitutively dis play high levels of HLA class II, as well as ICAM-1 and LFA-3 antigens . This suggests that the suppressive effect of the cytokine was not me rely related to an impaired up-regulation of these molecules. Addition of IL-1 during the MELR potentiated the allogeneic T cell proliferati on and could reverse, at least partly, the inhibitory effect of IL-10. Collectively, these data indicate that IL-10 can prevent the alloreac tion induced by human dendritic cells, providing new insights into the potential clinical use of this cytokine.