T-CELL-MEDIATED TERMINAL MATURATION OF DENDRITIC CELLS - LOSS OF ADHESIVE AND PHAGOCYTOTIC CAPACITIES

Dendritic cells (DC) are a specific subset of APC characterized by the potent ability to activate immunologically naive T cells, We have obs erved previously that the murine epidermis-derived DC line XS52 underg oes a set of profound changes upon Ag-specific interaction with T cell s, including IL-1 beta secretion, acquired expression of CD86, and los t expression of CD115 (CSF-1 receptor) and proliferative responsivenes s to CSF-1, These changes, which appear to reflect a critical transiti on during Ag presentation, have been termed T cell-mediated ''terminal maturation'' of DC, Here we report that XS52 cells also lose their ad hesive and phagocytotic capacities during this event, XS52 cells ordin arily adhere to petri dishes and phagocytose latex beads, as has been reported for DC freshly procured from spleen and skin. importantly, XS 52 cells lose both capacities after 3 to 24 h of incubation with HDK-1 T cells (keyhole limpet hemocyanin-specific Th1 clone) or with 5S8 T cells (dinitrobenzene sulfonate-specific Th0 clone) in the presence of Ag, By contrast, incubation with T cells alone or with Ag alone has m inimal effects, indicating that this regulation required both T cells and Ag, With respect to mechanisms, several lines of evidence suggest that IFN-gamma, which is secreted by T cells, serves as the primary me diator in down-regulating both capacities. Our observations illustrate a unique mechanism by which responding T cells, upon Ag-specific acti vation by DC, suppress the machinery of Ag uptake through the elaborat ion of IFN-gamma.