TRANSPLANTED SICKLE-CELL DISEASE PATIENTS WITH AUTOLOGOUS BONE-MARROWRECOVERY AFTER GRAFT FAILURE DEVELOP INCREASED LEVELS OF FETAL HEMOGLOBIN WHICH CORRECTS DISEASE SEVERITY

Bone marrow transplantation (BMT) is the only curative therapy for sic kle-cell disease (SCD), but is not devoid of failure risk. Nine patien ts with severe SCD were grafted in our institution between 1988 and 19 93. Six patients successfully engrafted, but three failed to engraft a nd had delayed autologous recovery. All patients had, prior to BMT, lo w levels of fetal haemoglobin (HbF less than or equal to 3 . 5%). No c hange in HbF occurred in successfully grafted patients. In the three p atients with graft failure HbF increased and remained persistently pre sent at a high level (greater than or equal to 22%) 14 months, 16 mont hs and 39 months post BMT, although two of the three patients were hom ozygous for either the Benin or the Central African Republic haplotype , a characteristic associated with low HbF level. Of interest, these t hree previously severely affected patients remain free of vaso-occlusi ve events. The mechanism responsible for the expression of high levels of HbF in our three patients with graft failure is not understood, bu t it protects them from the recurrence of severe vaso-occlusive crises .