IL-10 INHIBITS ICAM-1 EXPRESSION ON HUMAN LANGERHANS CELLS BUT NOT ONKERATINOCYTES, DERMAL ENDOTHELIAL-CELLS OR FIBROBLASTS

Intercellular adhesion molecule-1 (ICAM-1) is regularly expressed or i nducible on all major cutaneous cell populations including Langerhans cells, keratinocytes, endothelial cells and dermal fibroblasts. ICAM-1 is induced in the skin under inflammatory conditions and plays an imp ortant role in the activation of T cells. Interleukin-10 (IL-10) is a pluripotent immunosuppressive cytokine that inhibits proliferation of T cells via inhibition of antigen-presenting cells including Langerhan s cells. We demonstrates that IL-10 inhibits baseline and also cytokin e-stimulated ICAM-1 expression on human Langerhans cells, which has pr eviously been shown in the murine system. No effect of IL-IO was seen on human dermal vascular endothelial cells, which like Langerhans cell s are also able to present antigen. Additionally, no inhibitory effect of IL-10 was observed on the ICAM-1 expression of keratinocytes and d ermal fibroblasts. As IL-10 only weakly suppresses MCH II on human Lan gerhans cells, inhibition of ICAM-1 and other accessory molecules by I L-10 seems to be an important mechanism inhibiting the antigen-present ing function of human Langerhans cells.