Prednisolone levels in plasma and leukemia cells during therapy of chronic lymphocytic leukemia

The capacity of chronic lymphocytic leukemia cells to concentrate prednisolone has been evaluated in vivo and in vitro employing a radioimmunoassay for prednisolone. No evidence to suggest that leukemia cells are capable of selectively concentrating glucocorticoid was found. The relative uptake of glucocorticoid by leukemia cells was found to be greater in vitro than in vivo. This may be attributable to differences in steroid bioavailability to cells. Substantially lower levels than previously reported of free prednisolone were found in plasma of patients receiving oral treatment with prednisolone. This may result from the failure in previous studies to remove derivatives of prednisolone and other steroids prior to assay for hormones.