Ig heavy chain CDR3 size diversities are similar after conventional peripheral blood and ex vivo expanded hematopoietic cell transplants

It is largely unknown whether the immune repertoire can be reconstituted su ccessfully after high-dose chemotherapy and transplantation using ex vivo e xpanded hematopoietic stem cell (HSC) grafts. It is critically important fo r the transplant outcome that immune repertoire reconstitution progresses a fter 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 vive expanded bone marrow (BM) HSC graft transpl ants 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 exa mined in five breast cancer patients who were transplanted with ex vive exp anded 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) met hodologies, it is shown that the contribution of the V-H families to the ov erall repertoire among healthy adults is highly variable and not always pro portional to V-H family member size, After both ex vive expanded HSC transp lants and conventional PBSCTs, the V-H CDR3 repertoires were limited in siz e 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 health y adults. No difference was seen between ex vive expanded HSC graft transpl ant recipients and conventional PBSCT recipients in V-H repertoire diversit y. In one patient there was a follow-up analysis 12 months after ex vive ex panded graft transplant, and the diversity of the V-H families was maintain ed, In all patients, the amino acid size of the CDR3 regions fell within ad ult limits at all time points post transplant, These results indicate that B cell repertoire regeneration after ex vive expanded hematopoietic cell gr aft transplants is similar to that seen after conventional PBSCT.