T-cell repertoire complexity after allogeneic bone marrow transplantation.

We analyzed the T-cell repertoire in patients transplanted with bone marrow from an HLA identical sibling by determining the TCR diversity through Vbeta-CDR3-size spectratyping with Vbeta/Cbeta- and Vbeta/Jbeta-specific primers. Using the Vbeta/Cbeta primers, we observed limited TCR diversity only in recipients of a T-cell-depleted graft, whereas the TCR diversity of patients transplanted with an unmanipulated graft seemed to be indistinguishable from the one of a normal individual. However, with Vbeta/Jbeta-specific primers, increase of the resolution by approximately 10-fold also allowed the detection of imbalances in the TCR repertoire of recipients of an unmanipulated graft. This demonstrates that when high numbers of T cells are cotransfused with marrow, the TCR repertoire is more complete but still not as complete as in normal individuals, thereby emphasizing the important role of coinfused mature T cells in the restoration of the T-cell compartment after bone marrow transplantation.