Monitoring and prognostic evaluation of sex-mismatched bone marrow transplantation by competitive PCR on Y chromosome sequences.

In one case out of four, allogeneic BMT concerns a male recipient and a female donor. The monitoring of sex-matched BMT can be carried out by PCR amplification on Y-specific chromosome sequences (YCS), whatever the hematological disease. Twelve patients with sex-mismatched non-T-depleted BMT were first studied through a qualitative PCR, which gave semi-quantitative results. When the qualitative PCR revealed YCS, a competitive amplification was performed in order to estimate the YCS amount in the patient blood sample. For the purpose of the study, we classified the patients in two categories according to the results obtained 9 months after BMT. For 10 patients, we did not detect any YCS amplification after this time. These patients were in complete cytogenetic and clinical remission. For the remaining two patients, we always found male DNA in their blood samples. These patients were in cytogenetic remission but relapsed and died 21 and 25 months after BMT. Our results suggest that the persistence of male cells in peripheral blood, even at the low rate of 1% or 0.1%, 1 year after sex-mismatched BMT, is a bad prognosis.