Study On Characteristics And Dynamics Of TCR Repertoire Early After Allo-HSCT

Purpose: The study aimed to analyze and profile the basic characteristics and dynamic expanding of the T cell immune repertoire early after allo-HSCT,and,meanwhile,to understand deeply the rules of T cell immune reconstitution at the level of TCR after transplantation and the relationship between the early T cell expansion and clinical complications,such as relapse,Gv HD and virus infection,and eventually,to explore their practical value and application prospect in clinical work.Methods: Thirty patients with hematological malignancies undergoing allo-HSCT were enrolled.The TCR? CDR3 was sequenced by NGS from the grafts at d0 and the peripheral blood at d28 and d61.The sequence data was combined with the clinical data of the patients who were followed up for 1 year for analysis.Based on the characteristics of the TCR immune repertoire and the purpose of the research,the T cell response index(TCRI)was creatively designed.Its characteristics were analyzed and then applied to the statistical analysis of the data.Results: 1.After allo-HSCT,the inverse Simpson diversity index of the TCR repertoire continued to decline(only p=0.01 between d0 and d61),and the clonality index continued to rise over time(p=0.001).The clonality index of the non-relapse group was significantly higher than that of the relapse group at d28(p=0.018).However,there was no significant difference between the a Gv HD and the non-a Gv HD groups,and between the CMV group and the non-CMV group.2.The TCRI200ab(the TCRI of top200 clones in the first month after HSCT),TCRI200bc(the TCRI of top200 clones in the second month after HSCT)and TCRI200ac(the TCRI of top200 clones in the first two months after HSCT)of the haplo group were all significantly higher than those of the non-haplo group(p=0.032,0.007,0.004,respectively).There was no significant difference in TCRI between the a Gv HD and non-a Gv HD,between the c Gv HD and non-c Gv HD,between the CMV and non-CMV groups,and between the EBV and non-EBV groups.Only the TCRI200 bc of the non-relapse group was significantly higher than the relapse group(p=0.006).3.When comparing the paired data,the TCRI200 ab was significantly higher than the TCRI200bc(p=0.027),but the TCRI200 ac was not significantly higher than the TCRI200bc(p=0.112).4.The cumulative recurrence rate of the TCRI200bc?1.0 group was significantly higher than the TCRI200bc<1.0 group(31.25% vs 0%,p=0.0323).The 1-year survival rate of the TCRI200bc?1.0 group was higher than the TCRI200bc<1.0 group,but there was no statistical difference(78.57% vs 56.25%,p=0.2813).5.There were many significant differences among the usage of VDJ segments at the three different time points,and the V segments had more difference,the J segments had the second,but the D segments had no difference.There were some differences in the usage of V and J segments at d61 between the non-relapse and relapse groups.But there was no significant difference in the amino acid composition at d61 between the non-relapse and relapse groups(p>0.05).6.The dominant clones in the second month after transplantation in the non-relapse group used more TRBV2,TRBV12-3,TRBJ1-1 and TRBJ1-5(p<0.01)than the relapse group,and there was no significant difference in the D segment.The TCR? CDR3 of the dominant clones in the non-relapse group had more glycine and less alanine(p<0.05).7.Gv L-related TCR clones shared some amino acid motifs among patients,such as NAGE and SYTT,and these Gv L-related clones with similar specificity were more prone to donor HLA restriction and had experienced more extensive but relatively weaker expansion.Conclusion: 1.The T cells of patients early after allo-HSCT are all derived from donor mature T lymphocytes in the graft.The diversity of these T cells declines and the clonality increases over time.2.The expansion of these T cells is mainly driven by homeostasis in the first month after allo-HSCT.The expansion in the second month is mainly driven by antigens,which is closely related to recurrence,but is not related to Gv HD or virus activation.3.Patients with TCRI200bc?1.0 will not relapse within 1 year after transplantation,and have a higher 1-year survival rate,suggesting that TCRI200bc?1.0 can be used as an indicator to quantify whether the Gv L effect is sufficient to prevent patients from relapse within 1 year.4.After transplantation,the Gv L-related T cell clones tend to use TRBV2,TRBV12-3,TRBJ1-1,TRBJ1-5 and other segments.They have some commonality among patients including motifs,and they produce immune effects in a broader and slightly weaker way.