Lymphocyte subset reconstitution after HLA-identical placental blood transplantation (PBT) or PBT plus bone marrow transplantation (BMT) in three children with beta-thalassemia major

The kinetics of circulating lymphoid cells were evaluated in three children suffering from beta-thalassemia major after HLA-identical sibling placenta l blood transplant (PBT) in one patient and placental blood plus bone marro w transplantation (BMT) in two patients. Recovery of the main lymphocyte su bsets, as determined by phenotype analysis of circulating PBMCs, was comple te within 2 months after transplant, NK (CD56(+)) cells were the first to a ppear in peripheral blood, followed by T (CD3(+), CD2(+), CD7(+)) and B (CD 19(+)) cells. Of the T lymphocytes, the CD8(+) were the first to reconstitu te, but recovery of CD4(+) cells was also rapid and within 6 months these T cells reached normal values, The expression of CD57 by NK or T cells was s lightly delayed. The evaluation of RA and RO isoform expression of the CD45 molecule showed a prevalence of the CD45RA antigen with a ratio of 2-3:1, In the PET only patient, T cells expressing the CD45RO antigen prevailed in the early post-transplant period. Severe or chronic GVHD was not observed. This experience demonstrates that reconstitution of lymphocyte subsets is successful in genetic hematological diseases after transplantation of HLA-i dentical placental blood or placental blood plus bone marrow from healthy o r heterozygous siblings.