The Molecular Characteristics of T-Cell Receptor Repertoire of Clonal Expansion of T Lymphocytes in Leukemia Patients after Haploidentical Bone Marrow Transplantation.

The clinical and experimental results indicated that the T cell immune reconstitution was slow after haploidentical hematopoietic stem cell transplantation and existed high rate of GVHD and infection. This study was to analyze the molecular characteristics of T cell clones during immune reconstitution in leukemia patients after haploidentical bone marrow transplantation (H-BMT). Reverse transcriptase-polymerase chain reaction (RT-PCR) amplified 24 subfamily genes of TCRVB from peripheral blood lymphocytes of nine leukemia patients underwent H-BMT, five normal donors as control. The PCR products were further analyzed by genescane to evaluate the clonality of VB subfamily and characteristics of CDR3 and usage rate in VB subfamily. The monoclonal bands which associated with GVHD obtained and sequenced. Compared the sequences of TCRVB CDR3 gene repertoire with other sequences associated with GVHD had been reported before. In +10~+19m, the usage of TCRVB subfamilies still restricted. It can detected that some VB subfamilies were missing, others expanded in monoclonal or oligoclonal. 4 patients in stable condition showed that 9~14 VB subfamilies expressed and more than 50 percent were polyclone. In other 5 patients which have GVHD or CMV-pp65(+), the usage of TCRVB decreased obviously(p<0.05), the express of CDR3 were monoclonal or oligoclonal, only 30 percent were polyclonal. No common monoclone VB subfamilies expressed. After treatment and GVHD controled, the usage of VB subfamilies was increased and CDR3 polymorphism increased in 2 patients. Analyzed the sequences associated with GVHD and found that none of the clones appeared to share any similarity in amino acid motif. In +10~+19m, the usage of TCRVB subfamilies still skewing. In stable condition, there were 9~14 VB subfamilies expressed and dominated by polyclones, in active condition, the express of VB subfamilies decreased and dominated by monoclones or oligoclones. A group of CDR3 molecules related to GVHD showed no common amino acid motif.