PRESENTATION OF SOLUBLE-ANTIGENS BY MAST-CELLS - UP-REGULATION BY INTERLEUKIN-4 AND GRANULOCYTE MACROPHAGE COLONY-STIMULATING FACTOR AND DOWN-REGULATION BY INTERFERON-GAMMA/

We recently showed that bone marrow-derived mast cells bore MHC class II molecules and could present antigens to specific T cell hybridomas. This article summarizes the effects of purified recombinant cytokines on the expression of MHC class II molecules by mast cells and on thei r antigen-presenting capacity. Since IL-3 is essential for mast cell g rowth, all the cytokines were analyzed in the presence of IL-3. IL-3 d ownregulated the production of Ia molecules, so that mast cells cultur ed in IL-3 alone had no antigen presenting ability. In contrast, IL-4 and IFN-gamma upregulated the production of MHC class II molecules, wh ile GM-CSF had no effect. The antigen-presenting capacity of IL-4-trea ted mast cells was substantially enhanced by incubating these cells wi th GM-CSF for 2 days. GM-CSF enhanced antigen presentation only in com bination with IL-4. The activation of mast cells was reversible and co uld not be repeated. Finally, incubation of IL-4- or IL-4/GM-CSF-treat ed mast cells with IFN-gamma led to almost complete inhibition of the antigen-presenting function. These findings provide new insights into the regulation of specific allergic responses. (C) 1995 Academic Press , Inc.