Research Of The Correlation Between Immune Reconstitution And Clinical Outcome After HLA-haploidentical Allogeneic Hematopoietic Stem Cell Transplantation

Objective:To explore the immune reconstitution regularity of CD3~+T,CD4~+T,CD8~+T,CD4~+CD8~+T,CD4~-CD8~-T,B cell,NK cells and NK-T cells of patients who confirmed acute leukemia and underwent HLA-haploidentical allogeneic hematopoietic stem cell transplantation(allo-HSCT)retrospectively,and investigated the correlation between those immune subsets and clinical outcome.clinical outcome included relapse,leukemia-free survival(LFS),graft-versus-host disease(GVHD),overall survival(OS),non-relapse mortality(NRM),and infections.Methods:We retrospectively collected clinical data,recovery of lymphocyte subsets and clinical outcome of patients underwent HLA-haploidentical allo-HSCT hospitalize in Sichuan Provincial People’s Hospital.Their underlying diseases were confirmed acute leukemia(AL),diagnosed between January 2015 and May 2020.Clinical data included age of recipients at allo-HSCT,recipients Gender,underlining diseases,disease status,infused CD34~+cell in graft,infused total nucleated cell(TNC)in graft and age of donors at allo-HSCT;Recovery of lymphocyte subsets included Peripheral blood samples were collected from 105 allo-HSCT recipients with immune cells subsets(CD3~+CD4~+helper T cells,CD3~+CD8~+cytotoxic T cells,CD4~+CD8~+double positive T cells,CD4~-CD8~-double negative T cells,CD19~+B cells,CD3~-CD16~+CD56~+NK cells and CD3~+CD16~+CD56~+NKT cells)analyzed by flow cytometry at days 30,60,90,180 after allo-HSCT;and the clinical outcome included relapse,leukemia-free survival(LFS),graft-versus-host disease(GVHD)which included acute graft-versus-host disease(a-GVHD)and chronic graft-versus-host disease(c-GVHD),overall survival(OS),non-relapse mortality(NRM),and infections(bacterial infection,fungal infection and cytomegalovirus(CMV)infection).Lymphocyte subsets count recorded by time sequence,to investigated the correlation between independent variables and clinical outcomes.Results:Relapse and LFS:(1)In the univariate and multivariate analyses:1)The reconstitution of CD4~+T on day 60 was negatively associated with relapse rate.2)CD8~+T-90d,CD8~+T-180d and CD4~+CD8~+T-180d were negatively associated with relapse rate,CD8~+T cells showed prognostic value in the aspect of relapse post-transplantation on day 90,while the predictive value of CD4~+CD8~+T appeared relatively late.3)CD8~+T-180 d and CD4~+CD8~+T-180 d were positively associated with LFS.It was CD8~+cells,together with CD4~+CD8~+T cell,that showed prognostic value in the aspect LFS as the time went by.(2)Survival analysis:1)Compared to patients with CD8~+T-180d at<810/uL,patients with CD8~+T-180d at≥810/uL had a lower 2-year expected relapse rate(13.70±4.62 vs33.24±9.28,P=0.021)and superior 2-year expected LFS rate(79.41±5.41 vs 50.15±9.55,P=0.007).2)Similarly,the patients with CD4~+CD8~+T-180 d at≥17/uL had lower2-year expected relapse rate(13.51±6,37 vs32.83±7.23,P=0.012)and superior 2-year expected LFS rate(78.81±7.21vs 59.83±7.02,P=0.020)compared to the patients with CD4~+CD8~+T-180 d at<17/u L.3)When we divide patients into three groups:“high”cells group(CD8~+T-180 d≥810cells/u L and CD4~+CD8~+T-180d≥17cells/uL),the“middle”cells group(CD8~+T-180d≥810cells/u L and CD4~+CD8~+T-180d<17cells/uL;CD8~+T-180d<810cells/uL and CD4~+CD8~+T-180d≥17cells/uL)and“low”cells group(CD8~+T-180d<810cells/uL and CD4~+CD8~+T-180d<17cells/uL);we found that“high”cells group had the lowest 2-year expected relapse rate(8.91±2.90 vs.20.11±7.05 vs.43.64±10.73,respectively,P=0.000)and best 2-year expected LFS rate(85.93±6,65 vs.60.83±8.44 vs.34.51±10.59,respectively,P=0.000)compared to other groups.OS:(1)CD4~+T cells recovery seemed to be a quite reliable and stable indicator from 60 d after transplantation and this result didn’t change over time in spite of the dynamic analysis.(2):The 2-year expected OS rate in patients with the CD4~+T-180 at≥300/uL was significantly higher than that of cases with the CD4~+T-90 at<300cells/μL after HSCT(87.64±5.29 vs.65.89±8.42,respectively,P=0.007).c-GVHD:Higher CD4~+T-180 d count recovery is associated with lower incidence of c-GVHD.Fungal infection:Higher infused CD34~+cell in graft is negatively correlated with the incidence of infection.With the recovery of immune reconstitution after transplantation,the recovery of CD4~+T-180 d and B-180 d is negatively correlated with the incidence of infection.Conclusion:(1)The reconstitution of different immune subsets after HLA-haploidentical allo-HSCT is different.(2)The CD4~+T cell reconstitution could predict better survival and lower c-GVHD while CD8~+T cell,together with CD4~+CD8~+T cell reconstitution could predict lower relapse dynamically in patients undergoing allo-HSCT.