Delayed recovery of CDR3 complexity of the T-cell receptor-β chain in recipients of allogeneic bone marrow transplants who had virus-associated interstitial pneumonia:: Monitor of T-cell function by CDR3 spectratyping

Background: In the T-cell receptor (TCR)-beta chain, complementary-determining region 3 (CDR3) contains specific peptide sequences essential for recognition. Diversity of this region is considered to contribute to immunocompetence in humans. Objective: The purpose of this study was to define the process of reconstitution of CDR3 complexity of the TCR-beta chain after allogeneic bone marrow transplantation and to investigate the association between host immunocompetence and CDR3 complexity. Methods: Diversity of the CDR3 region of the TCR-beta chain was examined by CDR3 size distribution analysis with the use of an automated DNA sequencer. Results: Reconstitution of the alpha beta T-cell repertoire and CDR3 diversity was incomplete for at least 2 months after bone marrow transplantation. Delayed reconstitution of T-cell diversity was more marked in immunocompromised hosts. Unlike the situation in patients who received allogeneic bone marrow grafts, the recovery of CDR3 complexity was almost perfect by 2 months after transplantation in patients who received allogeneic blood stem cells. Clonal expansion of alpha beta T cells after allogeneic bone marrow transplantation was readily detected by CDR3 size spectratyping analysis. Conclusion: PCR-based CDR3 size spectratyping may be a useful tool for clinically monitoring immune reconstitution after allogeneic hone marrow transplantation.