At one month after transplantation, there was progressive improvement in TCR Vβ repertoire diversity in all cases ( 15). Significant immune renewal example data have come from comparisons of TCR repertoires in patients with severe combined immunodeficiency (SCID) before and after HSCT. In addition, this effective technique has been used to compare quantifications of TCR repertoire recovery between different types of HSCTs, such as allogeneic or autologous HSCT, cord blood (CB) or peripheral blood (PB) HSCT, unrelated donor (UD) or related donor HSCT, haploidentical HSCT (haplo-HSCT), and T-cell-depleted (TCD) HSCT ( 8- 14). Until now, TCR repertoire diversity analysis has been a common method for characterizing immune reconstitution after HSCT and analyzing the oligoclonal expansion of T cells during virus infection, graft-versus-leukemia (GVL) effects, and graft-versus-host disease (GVHD). Since the early 1990s when the TCR repertoire analysis technique of using polymerase chain reaction (PCR)-based CDR 3 size spectratyping and DNA sequencing, or PCR-Genescan, was established, TCR repertoire analysis has been used to evaluate the recovery of immune repertoires after HSCT. Recovery of diversity of TCR repertoire in patients after HSCT This type of evaluation can help to characterize the features of the host T cell immune status and identify T cell populations of interest in cancer and peripheral immune reconstitution after HSCT ( 5- 7). Therefore, analysis of TCR repertoires could provide a global picture of the distribution and clonal expansion of TCR subfamilies in patients and normal individuals. Overall, such a TCR rearrangement makes up 10 16 to 10 18 diverse TCR repertoires. The mechanisms of such recombinations are mediated by a recombinase that recognizes recombination signal sequences (RSSs) and brings the exons together. For example, in the TCR β chain, nucleotide transferases add or remove nucleotides at various Vβ-Dβ and Dβ-Jβ junctions during the recombination process, and the CDR3 region of the Vβ-Jβ combination may vary in length by as many as 6-8 amino acids ( 4). CDR3 is involved in the response to specific interactions with antigenic peptides. The variable domains of TCRs are assembled by the somatic recombination of one variable (V), diversity (D, only for β or δ chain), and joining (J) segment each, and they comprise three hypervariable or complementarity-determining regions (CDR1, CDR2, CDR3) within the TCR. Each TCR chain, similar to the immunoglobulin (Ig) heavy and light chains, is encoded by multiple gene segments. TCRs are specific for antigen recognition in conjunction with major histocompatibility complex (MHC) molecules, leading to T cell activation and proliferation. The TCR includes the α, β, γ and δ chains, which form α/β or γ/δ heterodimeric chains that are expressed on mature T cell surfaces. Therefore, dynamic analysis of the TCR repertoires of T cells in patients after HSCT is important for estimating the immune reconstitution in different clinical situations. While the recovery of peripheral T cells occurs in transplant recipients via thymus-dependent and thymus-independent pathways, the regeneration of a population of phenotypically naive T cells with a broad T cell antigen receptor (TCR) repertoire relies entirely on the de novo generation of T cells in the thymus ( 1), however, early T cell reconstitution also depends on the persistence and function of T cells that are adoptively transferred with grafts ( 2, 3). Moreover, immune reconstitution is one of the primary factors that determines long-term prognosis following transplantation, particularly T cell immune reconstitution, which is important for disease relapse and virus infection. Favorable outcome for HSCT depends on either complete hematopoietic or immune reconstitution. Hematopoietic stem cell transplantation (HSCT), including allogeneic HSCT and autologous HSCT, is performed to treat a broad spectrum of illnesses. Received: 17 July 2015 Accepted: 19 August 2015 Published: 28 September 2015. Keywords: Hematopoietic stem cell transplantation (HSCT) T cell receptor (TCR) repertoire diversity immune reconstitution Policy of Dealing with Allegations of Research Misconduct.Policy of Screening for Plagiarism Process.
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