Investigate T-lymphocyte Subsets Reconstitution And Analysis Of T-cell Receptor Excision DNA Cycles In Patients After Unrelated Cord Blood Transplantation

Object: The study was to investigate the T lymphocyte reconstitution in patients afterumbilical cord blood transplantation，and establish the technique of T~-cell receptorexcision DNA circles(TRECs)detection，thereby to accurately understand cellularimmunodeficiency and the capacity and potential of long~-term immune reconstitution ofUCBT patients.Method:We have observed peripheral blood lymphocyte subsets reconstruction of21patients who accepted the umbilical cord blood transplant by using five colorflow~-cytometric analysis,and compared reconstruction of T~-cells with6cases whoaccepted allogeneic peripheral blood/bone marrow stem cell transplantation and5casesof healthy control. The lymphocyte subsets proportion in peripheral blood lymphocyteafter transplantation is studied on the day when patients are implanted,1、2、3、4、6months after transplantation respectively，and quantitative detection of T~-cell receptorexcision DNA circles (TRECs) in DNA of PBMCs,In order to further clarify whichsubsets play graft~-versus~-tumor effects after umbilical cord blood transplantation,lymphocyte subsets of different graft are compared. In order to further clarify whichsubsets play graft~-versus~-tumor effects after umbilical cord blood transplantation,lymphocyte subsets of different graft are compared.Result In our study,.CD4~+T subsets of the proportion of the peripheral bloodlymphocyte in patiens who accepted the umbilical cord blood transplant have decreased obviously since implantation. The CD4~+T subsets on the day2months aftertransplantation decreas to the minimal point （15.24±11.43）%, then gradually rise，but cannot reach to normal until6months after transplantation. CD8~+T subsets is wellreconstituted,and rise to normal during implantation，with a low CD4:CD8ratio overthe first6months after transplantation. The CD3~+、CD4~+、CD8~+T lymphocyte countsin sPB/BMT patients is higher than UCBT group within implantation to2monthsafter transplantation,especially in1month after transplantation have statistic differences（0.169±0.067）vs（1.068±0.474）、（0.092±0.063）vs（0.199±0.083）、（0.076±0.017）vs（0.882±0.417）（p<0.05），but it reversed2months after transplantation until6months.On the day6months after transplantation the results are(2.56±0.39)vs(1.66±0.36)、（0.83±0.19）vs（0.55±0.29）、（1.45±0.24）vs（0.92±0.15）but it is not have significantly statistic differences.In all27patients， the memory T~-cells subsets （CD45RA~-CD62L~+、CD45RA~-CD62L~-、 CD45RA~+CD62L~-) reconstituted faster than na ve T~-cellssubsets（CD45RA~+CD62L~+）. It is rapid expansion in the early phase after transplantation.Early na ve T~-cells expansion in UCBT was thymic~-independent, It is reached thelowest phase during2months after UCBT and then slowly increased. But it cannot reachto normal on the day6months after transplantation. We observed an unprecedented increasedCD4~+TTD~-cells(terminally differentiated effector memory，TTD，CD45RA~+CD62L~-)reconstitution in UCBT group，it is significantly higher than sPB/BMT group andnormal control in any phase after transpltation.During2and3month afer transpltation,TCM（CD45RA~-CD62L~+）and TEM（CD45RA~-CD62L~-） lymphocyte subsets havestatistic differences in two groups.(P<0.05)Assessment of TRECs in UCBT and sPB/BMT transplant recipients demonstratesreduced thymic function，it is undetected during1month， post~-CBT thymopoieticrecovery that was measurable in only1subjects and2recipients in sPB/BMT group in3month after transpltation. All TRECs present in recipients is lower than healthy control subjects who were age~-matched.Conclusion The T lymphocyte subsets renconstituted slowly in early phase aftertransplantation.The CD8~+T~-cells renconstituted faster than CD3~+and CD4~+T~-cells. It ItIt is rapid shift from naive to memory phenotype in two groups after transplantation. Weobserved an unprecedented increased CD4~+TTD~-cells reconstitution in UCBT group.Thymic function is reduced in early phase after transplantation,and TRECs cannot bewell detected.