Prediction of azathioprine intolerance in transplant patients.

One cause of transplant rejection is curtailment of immunosuppressive therapy due to leucopenia. To determine those patients most apt to develop leucopenia due to azathiprine the granulocyte response to intravenous injections (i.v.) of hydrocortisone was evaluated in 10 patients who had rejected their grafts at least six month previously. 5 patients who had rejected their grafts with concomitant severe leucopenia had an inadequate response to hydrocortisone, while in the other 5, who had tolerated the drug, the response was similar to that of normal controls. Based on these observations, all the transplant candidates underwent the hydrocortisone stimulation test the results of which were correlated with their subsequent clinical course. All medical decisions were based on events other than the steroid test. 8 leucopenic patients underwent splenectomy. 6 improved their granulocyte response to hydrocortisone and tolerated azathioprine after transplantation. 2 patients who underwent splenectomy and an unoperated leucopenic man were unresponsive to the hydrocortisone test, did not tolerate azatioprine after transplantation and rejected their grafts. 4 candidates with normal responses to i.v. hydrocortisone received transplants uneventfully. In all 13 patients transplanted since the beginning of this study, the hydrocortisone test correctly predicted their tolerance to azathioprine.