Ex vivo-expanded hematopoietic cell graft recipients exhibit T cell repertoire diversity similar to that seen after conventional stem cell transplants

The feasibility of using ex vivo-expanded hematopoietic progenitor cells to reconstitute hematopoiesis after high-dose chemotherapy is presently being examined. Early studies have shown that myeloid and erythroid hematopoiesi s can be successfully reconstituted after high-dose chemotherapy and ex viv o-expanded hematopoietic cell transplantation. The lymphoid reconstitution, however, has not been addressed previously. In this study, we examined the diversity of the T cell receptor V beta chain (TCRBV) repertoires in 5 bre ast cancer patients who were transplanted with ex vivo-expanded bone marrow mononuclear cells as the only source of hematopoietic graft. Using the TCR BV third complementarity determining region (CDR3) fingerprinting methodolo gy, it is shown that CD4(+) and CD8(+) T cell subsets after ex vivo-expande d hematopoietic cell graft transplants exhibit TCRBV diversities that are s imilar in complexity when compared to those seen after conventional autolog ous peripheral blood stem cell transplants (PBSCT). No apparent difference in the extent of CDR3 diversity was found between ex vivo expanded and conv entional autologous PBSCT recipients when the CD4(+) and CD8(+) subsets wer e further separated into CD45RA(+) "naive" and CD45RO(+) "memory" subsets. The diversity of the CD45RA(+) naive subsets was as complex as that of the CD45RO(+) memory subsets. These results indicate that T cell repertoire div ersification is not further compromised when ex vivo-expanded hematopoietic cells are used instead of autologous peripheral blood stem cells as the on ly source of graft.