CD4(+) Epstein-Barr virus-specific cytotoxic T-lymphocytes from human umbilical cord blood

Umbilical cord blood (CB) is increasingly used for allogeneic hematopoietic stem cell transplantation. To determine whether viral antigen-specific cytotoxic T-lymphocytes (CTL) could be generated from the predominantly naive T-cell populations in CB, CB-derived mononuclear cells were stimulated with autologous Epstein-Barr virus (EBV) transformed B-lymphoblastoid cell lines over several weeks in the presence of recombinant human interleukin-2 (IL-2). By 28 days of culture, T-lymphocytes from all six CB that had been treated with IL-2 displayed EBV-specific cytotoxicity. These cells were largely CD4(+), with complete inhibition of cytotoxicity by anti-CD3 and variable inhibition by anti-HLA DR monoclonal antibodies. The EBV-specific effectors were cloned by limiting dilution, and most of the CTL clones were CD4(+). The cytotoxicity of the CB-derived CD4(+) CTL clones was inhibited by EGTA but not by anti-Fas ligand mAb, suggesting that this cytotoxicity was mediated by perforin/granzyme B. These data indicate that virus-specific CTL can be cultivated and cloned from CB, a human T-cell source that may not have prior in vivo antigenic exposure or reactivity. This finding may have applications in adoptive immunotherapy to recipients of CB transplants.