Cytoplasmic receptor levels and glucocorticoid response in human lymphoblastoid cell lines

The cytolethal response to treatment with prednisolone was investigated in vitro in eight human lymphoblastoid cell lines containing varying concentrations of specific cytoplasmic glucocorticoid receptors. A similar response was observed in seven of the lines irrespective of their concentration of cytoplasmic receptors and pharmacological doses of steroid, well above those required to saturate receptors in cell-free extracts, were required for a massive lethal response. One cell line derived from Burkitt's lymphoma was refractory to lethal effects even with pharmacological doses of steroid. A similar unresponsiveness to the cytolethal effect of prednisolone in vitro was observed in fresh lymphoblasts derived from patients with acute lymphoblastic leukaemia despite evidence of a satisfactory clinical response to therapy which included steroid. The resistance of human lymphoblastoid cells to treatment with glucocorticoids in vitro may result from a defect in activation subsequent to the binding of steroid to cytoplasmic receptors.