The Molecular Characteristics of T-Cell Immune Reconstitution in Leukemia Patients after Allogeneic Hematopoietic Stem Cell Transplantation.

The clinical and experimental results indicated that the T cell immune reconstitution was slow after hematopoietic stem cell transplantation. This study was To analyze the molecular characteristics of T lymphocytic clones during immune reconstitution in leukemia patients after allogeneic hematopoietic stem cell transplantation(Allo-HCST)by investigating complementarity determining region (CDR3) repertoires of T cell receptor β chain variable region (TCRVB) and made it possible to understand the relationship between the express of TCRVB and immune reconstitution. Reverse transcriptase-polymerase chain reaction(RT-PCR) amplified 24 subfamily genes of TCRVB from peripheral blood lymphocytes (PBLs) of twenty-four patients with leukemia underwent three kinds of Allo-HSCT(haploidentical bone marrow transplantation, matched sibling bone marrow transplantation and matched-unrelated PBSCT), five normal donors as control. The PCR products were further analyzed by genescane to evaluate the clonality of VB subfamily. The monoclonal bands which associated with GVHD and CMV infection were obtained through denaturation polyacrylamide gel electrophoresis and sequenced. Compared the sequences of TCRVB CDR3 gene repertoire with other sequences associated with GVHD or CMV infection which had been reported. +2~+19months after transplantation, for nine patients among them which underwent haploidentical bone marrow transplantation, there were 6~14 VB subfamilies expressed with 33% 15 VB subfamilies expressed, which 45%of them were polyclones. In the 5 patients of matched-unrelated PBSCT, there were 10~15 VB families expressed, with 45% the polyclone expression. For ten patients underwent matched sibling bone marrow transplantation, 10~16 VB subfamilies expressed and more than 48% were polyclones. Monoclones and oligoclones existed in 24 VB subfamilies, no common monoclone VB subfamilies expressed. According to the usage of VB family and polyclonal expression, Immune reconstitution in patients which underwent haploidentical BMT was later than that of other two groups (p<0.05), there were no different between other two groups (p>0.05). After Allo-HSCT, two patients detected TCRVB in +2m and +3m and found that it has tendency of adding to use VB subfamilies and increasing to express CDR3 polymorphism. Using biology-information tool, compared 23 TCRVB CDR3 molecules which related to GVHD and CMV infection and found that, different cases in the same VB subfamilies may share similarity in amino acid motif, while in different VB subfamilies none of clones appeared to share the same amino acid motif. In 1.5 years after AHSCT, the usage of TCRVB subfamilies still restricted. T-cell immune reconstitution in patients which underwent haploidentical BMT was later than that of other two groups. TCRVB CDR3 molecules which related to GVHD and CMV infection showed that different cases in the same VB subfamilies may share similarity in amino acid motif, while in different VB subfamilies none of clones appeared to share the same amino acid motif.