¹The University of Texas Health Science Center, San Antonio, TX, USA

²South Texas Cancer Institute, San Antonio, TX, USA

³VU Academic Hospital, Amsterdam, Netherlands

⁴Aastrom Biosciences, Inc, Ann Arbor, MI, USA

Correspondence to: Dr J M Teale, Department of Microbiology, Mail Code 7758, The University of Texas Health Science Center at San Antonio, 7703 Floyd Curl Drive, San Antonio, TX, 78229-3900, USA

It is largely unknown whether the immune repertoire can be reconstituted successfully after high-dose chemotherapy and transplantation using ex vivo expanded hematopoietic stem cell (HSC) grafts. It is critically important for the transplant outcome that immune repertoire reconstitution progresses after ex vivo expanded HSC graft transplants at least as efficiently as that seen after conventional HSC transplants. Previously, we showed that the T cell receptor V beta (TCRVB) third complementarity determining region (CDR3) diversification after ex vivo expanded bone marrow (BM) HSC graft transplants was similar to that seen after conventional peripheral blood stem cell transplants (PBSCTs). In the present study, the CDR3 diversity of the six immunoglobulin (Ig) heavy chain variable region gene (V_H) families was examined in five breast cancer patients who were transplanted with ex vivo expanded BM HSCs as the only source of stem cells. For comparison, 12 healthy adults and four conventional PBSCT recipients were also studied. Using both CDR3 fingerprinting and single strand conformation polymorphism (SSCP) methodologies, it is shown that the contribution of the V_H families to the overall repertoire among healthy adults is highly variable and not always proportional to V_H family member size. After both ex vivo expanded HSC transplants and conventional PBSCTs, the V_H CDR3 repertoires were limited in size diversity at 6 weeks post transplant. By 6 months, however, V_H families displayed a repertoire diversity that was as complex as that seen in healthy adults. No difference was seen between ex vivo expanded HSC graft transplant recipients and conventional PBSCT recipients in V_H repertoire diversity. In one patient there was a follow-up analysis 12 months after ex vivo expanded graft transplant, and the diversity of the V_H families was maintained. In all patients, the amino acid size of the CDR3 regions fell within adult limits at all time points post transplant. These results indicate that B cell repertoire regeneration after ex vivo expanded hematopoietic cell graft transplants is similar to that seen after conventional PBSCT. Bone Marrow Transplantation (2001) 27, 413-424.

transplantation; B lymphocytes; repertoire; diversity; lymphopoiesis