[Cord blood transplantation with two mismatched HLA loci in a child with acute lymphoblastic leukemia in second remission: follow-up of minimal residual disease using a clone-specific probe].

A 9-year-old girl with acute lymphoblastic leukemia in second remission underwent cord blood transplantation (CBT) from an HLA-mismatched (2 loci by serotype, 3 loci by genotype) unrelated donor. The infused nucleated cell count was 1.95 x 10(7)/kg. FK506 and mini-MTX were used to prevent graft-versus-host disease (GVHD), but grade II acute GVHD developed on the skin (stage III). The GVHD subsided after administration of corticosteroid, but marked hyperglycemia developed, which required transient insulin therapy for its control. Minimal residual disease (MRD) was assessed using a clone-specific probe for the JH region. MRD was positive before CBT, but became negative one month after CBT. Now, at 14 months after CBT, the patient is in a disease-free state without detectable MRD. These observations suggest that CBT with two mismatched HLA loci can be performed safely, and that sequential analysis of MRD is useful for evaluation of the disease status after CBT.