Effect of dexamethasone on the growth of human lymphoblastoid cell lines

Effect of dexamethasone of the growth of two T-cell acute lymphoblastic leukemia (T-ALL) cell lines, JM and TALL-1 and an American Burkitt lymphoma cell line, Ramos, of B-cell type was examined. While the growth of both TALL-1 and Ramos cell lines was significantly inhibited by dexamethasone at the concentration of 10(-7) M, JM cell line was markedly resistant at the high concentration of 10(-5) M of dexamethasone. The assay of glucocorticoid receptors showed that a small amount of the binding site was found in both T-cell leukemia cell lines, JM and TALL-1 and that a moderate amount of the binding site was found in Ramos cell line. Thus, glucocorticoid sensitivity (growth inhibition of these leukemia-lymphoma cell lines by dexamethasone) did not correlate with either the number of glucocorticoid receptor or with surface membrane markers of the target cells. This result suggests further marked heterogeneity of leukemic cells.