INFLUENCE OF GRAFT-VERSUS-HOST DISEASE ON THE ERADICATION OF MINIMAL RESIDUAL LEUKEMIA DETECTED BY POLYMERASE CHAIN-REACTION IN CHRONIC MYELOID-LEUKEMIA PATIENTS AFTER BONE-MARROW TRANSPLANTATION

To evaluate the remission quality of Philadelphia chromosome (Ph)-posi tive, BCR/ABL-positive CML patients after allogeneic bone marrow trans plantation (BMT) we used the polymerase chain reaction (PCR) to detect BCR-ABL specific RNA in addition to Southern blotting, cytogenetic, a nd hematological investigation. Fifty-five bone marrow samples of 27 p atients in clinical remission were studied by PCR, 0.5 to 99 months (m edian 8 months) after BMT. The median clinical follow-up of this cohor t of patients is 24 months (1-109) after BMT. BCR-ABL transcripts coul d be detected in 16 out of 27 patients (59%). Risk factors for minimal residual leukemia (MRD) as defined by PCR were the kind of graft-vers us-host disease (GvHD) prophylaxis (patients with T-cell-depleted graf ts had a higher rate of MRD in comparison to patients treated with met hotrexate/cyclosporin A) and the presence or absence of GvHD after BMT (patients without GvHD had a higher incidence of MRD than patients wi th GvHD). Moreover, the detection of minimal residual leukemia had pro gnostic significance. Out of 16 patients with minimal residual leukemi a as detected by PCR, four patients relapsed clinically and two furthe r cases relapsed cytogenetically. In contrast nons of the patients lac king evidence of minimal residual leukemia relapsed. Serial PCR analys is may prove helpful in deciding about further therapeutic interventio ns (e.g. interferon therapy or adoptive immunotherapy) before leukaemi c relapse becomes manifest after BMT.