OBJECTIVETo study the CDR3 spectratyping and clonal expansion of T cells in the peripheral blood mononuclear cells (PBMCs) of patients with beta-mediterranean anemia patient undergoing allogeneic peripheral blood stem cell (PBSC) transplantation.

METHODSThe total RNA was isolated from the PBMCs of a nine-year-old boy with beta-mediterranean anemia before and after PBSC transplantation, and at the time of occurrence of graft-versus-host disease (GVHD). The CDR3 length was analyzed using immunoscope technique, and the characteristics of the T cell receptor (TCR) on the T cells with clonal expansion were examined by gene sequencing.

RESULTSThe 24 TCR BV CDR3 repertoire showed Gaussian distribution in the PBMCs isolated before the transplantation, and some of the TCR BV family CDR3 showed skewing in the PBMCs isolated 23 days after transplantation and at the onset of GVHD (28 days after transplantation), suggesting the clonal expansion of the donor PBSCs.

CONCLUSIONThe host PBMCs show muti-clonal expansion 23 days after PBSC transplantation, and in the stage of GVHD, some of the TCR BV family T cells show significant monoclonal expansion. Analysis of TCR CDR3 spectratyping and the molecular characteristics of specific TCR may help evaluate the immune reconstitution following the transplantation and indicate specific treatment for potential GVHD.