Opposite effects of dexamethasone on antitumor and natural suppressor activities of bone marrow cells

Effects of dexamethasone on the ability of nonadherent bone marrow cells to inhibit proliferation of mastocytoma P815 cells and concanavalin A-stimulated proliferation of syngeneic splenocytes were studied. Antitumor activity of cells increased, but their natural suppressor activity decreased in the presence of dexamethasone. Pretreatment with dexamethasone (for 3 h) did not affect the sensitivity of mastocytoma cells to antitumor factors and the antitumor activity of bone marrow effectors. Pretreatment of bone marrow cells with dexamethasone for 24 h potentiated antitumor activity of their nonadherent fractions. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 129, No. 4, pp. 459–461, April, 2000