Interstitial pneumonitis in acute leukemia patients submitted to T-depleted matched and mismatched bone marrow transplantation.

PURPOSE: To identify factors that could contribute to interstitial pneumonitis (IP), which remains one of the major causes of morbidity and mortality after both matched and mismatched bone marrow transplantation (BMT). METHODS AND PATIENTS: Ninety acute leukemia patients received an allogeneic T-depleted matched (n = 54) or mismatched (n = 36) BMT. They were preconditioned with total body irradiation (TBI), thiotepa, rabbit anti-thymocyte globulin, and cyclophosphamide. The TBI scheme was hyperfractionated in matched, and a single dose in mismatched patients. The dose to the lungs was reduced in both groups. RESULTS: Five of the 54 matched patients developed IP. All cases were fatal. There were 16 cases of IP, 13 fatal, in the mismatched group. The probability of developing IP was 11.3 +/- 4.9% and 48.6 +/- 9.0%, respectively. The between-group difference was statistically significant (p < 0.0001). The type of transplant and the TBI scheme were the most important parameters for IP development in univariate analysis, whereas acute graft-versus-host disease, disease stage and sex were nonsignificant. Median follow-up was 342 days (range 17-2900). CONCLUSIONS: The low incidence of IP in matched patients and the lack of idiopathic cases are evidence for the validity of the TBI schedule. In contrast, the incidence in mismatched patients remains too high; therefore, new strategies should be studied in an attempt to lower it.