Analysis of immune reconstitution in children undergoing cord blood transplantation

Objective. The aim of this study was to investigate and compare immune reco nstitution in allogeneic cord blood transplantation (CBT) and bone marrow t ransplantation (BMT) recipients. Patients and Methods. Twenty-three children underwent CBT from either human leukocyte antigen-identical siblings (11 cases) or unrelated donors (12 ca ses) were enrolled in the study, together with 23 matched children receivin g BMT. Patients were analyzed 2-3 and 12-15 months after transplant. Recove ry of T-, B-, and NK-lymphocyte subsets, proliferative in vitro response to mitogens, as well as cytotoxic activities, were investigated. Results. CBT recipients showed a marked increase in the number of B lymphoc ytes as compared with patients who underwent BMT (p < 0.001). The absolute number of CD3(+) and CD8(+) T cells, as well as the proliferative response to T-cell mitogens, recovered with time after transplantation, irrespective of the source of stem cells used. Recipients of unrelated CBT had a better recovery of CD4(+) T lymphocytes (p < 0.01). Among patients experiencing a cute graft-versus-host disease (GVHD), children given CBT had a much greate r production of CD4(+) CD45RA(+) T cells than BMT recipients (p < 0.005). R ecovery of NK cell number end innate cytotoxic activities was fast, irrespe ctive of the source of stem cells used. Conclusions. Despite the much lower number of lymphocytes transferred with the graft, recovery of lymphocyte number and function toward normal in CBT recipients was rapid and comparable to that observed after transplantation of bone marrow progenitors. This prompt immune recovery possibly was favore d by the reduced incidence and severity of GVHD observed in children who un derwent CBT. (C) 2001 International Society for Experimental Hematology. Pu blished by Elsevier Science Inc.