The effect of dexamethasone on growth and differentiation of bone-marrow derived mucosal mast cells in vitro.

An in vitro culture system was used to investigate the effects of dexamethasone on the production of mucosal mast cell (MMC) growth activity from T cells, and the proliferation and maturation of MMC in culture. The addition of dexamethasone (Dex) to cultures of lymphocytes from Nippostrongylus brasiliensis (Nb.)-infected rats suppressed production of MMC growth activity, as assessed by the lack of MMC growth and differentiation when supernatants of the treated lymphocyte cultures were added to normal rat bone-marrow cultures. Dexamethasone treatment of normal rat bone-marrow cultures affected the maturation of the bone-marrow derived MMC by preventing normal granule development. The ratio of neutrophils:macrophages present in the cultures was also altered. Dexamethasone did not have any detectable effect on mature MMC in culture.