Steroid suppression of protein synthesis of activated human lymphocytes

In vivo and in vitro studies of the effect of methylprednisolone on protein synthesis of activated lymphocytes has been carried out using [³H]leucine incorporation into lymphocytes as the assay system. PHA and allogeneic cells (two-way MLC) were used to activate the lymphocytes in vitro. It was found that 5 μg/ml of methylprednisolone produced a significant reduction in [³H]leucine incorporation and that higher concentrations did not increase the suppressant effect. Lower concentrations often did produce the same magnitude of suppression. SPS during the MLC was inhibited to a greater extent and at lower concentrations of methylprednisolone than PHA-activated lymphocytes. Patients on maintenance immunosuppression with normally functioning renal allografts had normal SPS responses to PHA. Patients with rejecting renal transplants receiving higher doses of immunosuppressive drugs often had diminished SPS responses to PHA.