Identification Of CD3^-CD56^dimCD16⁺NK Cell Subsets After Unrelated Cord Blood Transplantation Early

Objective The objective is to identify the characteristics of NK cells subsets ofCD3^-CD56^dimCD16⁺during early NK cell reconstitution after leukemia patients receiveunrelated cord blood transplantation （UCBT） treatment.Methods16leukemia patients who received hematopoietic stem cell transplantationare selected.10of them received unrelated cord blood transplantation, including6male,5female, aged4³6（18.6±10.85） years old. The other6received allogeneicperipheral blood or bone marrow stem cells transplantation, including2male,4female,and aged2.5⁵8（22.58±20.45） years old. Use eight color flow cytometry technique todetect NK cell subsets in fresh peripheral blood samples of patients respectively aftertransplantation,1months later,2months later,3months later and monitor CD57, CD11band CD27receptors generated on the surface of subset cell CD3^-CD56^dimCD16⁺. Byreconstruction of two early NK cell of transplantation patients, comparing andanalyzing the reconstruction of unique NK subset cell CD3^-CD56^dimCD16⁺, we canfurther identify characteristics of NK cell subsets and especially its unique subsetCD3^-CD56^dimCD16⁺cell after UCBT and initially study the function of such cell group.Results1. Reconstruction rules of early NK cell subsets of CD3^-CD56^dimCD16⁺afterunrelated umbilical cord blood transplantation: compared with allogeneic peripheralblood/bone marrow stem cell transplantation group, after patients received umbilicalcord blood transplantation, in the early stage, reconstructed NK cell subgroupCD3^-CD56^dimCD16⁺is gradually increased from beginning. Two months after transplantation the ratio of its amount versus peripheral blood lymphocyte significantlyincreased （16.46±11.05）%vs （8.56±5.58）%（P<0.05）. The growth law of theabsolute value of CD3^-CD56^dimCD16⁺NK cell subsets is similar to the growth law ofthe proportion it accounts for the peripheral blood lymphocytes, and significantly higherthan absolute value of allogeneic peripheral blood/bone marrow stem celltransplantation group CD3^-CD56^dimCD16⁺NK cells subsets of the same period.2.After unrelated umbilical cord blood transplantation, expression of subsets ofCD57, CD11b and CD27on the surface of NK cell receptor CD3^-CD56^dimCD16⁺: aftercord blood transplantation, in the early stage, the expression of CD57receptor on thesurface of NK cell subsets of CD3^-CD56^dimCD16⁺to peripheral blood lymphocyte hasbeen lower than normal control group （16.87±4.57）%vs （42.57±23.84）%（P<0.05）since the implantation. And the ratio of it to peripheral blood lymphocyte and itsabsolute value is lower than that of the same period in allogeneic peripheral blood/bonemarrow stem cell transplantation group. The ratio of the expression of CD11b receptoron the surface of CD3^-CD56^dimCD16⁺NK cell subsets in UCBT group to peripheralblood lymphocyte at the time of implantation （87.17±15.65）%vs （45.25±13.09）%（P<0.01） and one month after transplantation is higher than that in allogeneic peripheral/bone marrow stem cell transplantation group, but then declined. Two, three monthsafter transplantation, it is lower than that in allogeneic peripheral blood/bone marrowstem cell transplantation group, and its absolute value since implantation has showedincreasing trend. Three months after transplantation, its absolute is obviously differencefrom that in the normal control group （0.069±0.051）×10⁹/L vs （0.009±0.005）×109/L（P<0.05）, significantly higher than that in allogeneic peripheral blood/bone marrowstem cell transplantation group （0.069±0.051）×109/L vs （0.018±0.01）×109/L（P<0.05）. The ratio of the expression of CD27receptor on the surface of NK cellsubsets of CD3^-CD56^dimCD16⁺to peripheral blood lymphocytes in umbilical cord bloodtransplantation group is of no big difference compared with that in allogeneic peripheral blood/bone marrow stem cell transplantation and its absolute value is slightlyincreased.Conclution1. The proportion of NK cells to peripheral blood lymphocyte aftertransplantation of unrelated umbilical cord blood in early reconstitution stage is highand absolute value is high, especially the ratio of CD3^-CD56^dimCD16⁺NK cell subsets inearly reconstruction stage after umbilical cord blood transplantation increasedsignificantly. So did the absolute value.2. The high expression of CD11b receptor, low expression of CD57andCD27receptor on the surface of CD3^-CD56^dimCD16⁺NK cell subsets in earlyreconstruction stage after unrelated umbilical cord blood transplantation suggest thecharacteristics of CD3^-CD56^dimCD16⁺NK cell subsets is immature NK cells, and it hasstrong killing power, but the cytokine secretion function is low. Relapse rate of high-riskpatients half year after UCBT transplantation was0. So we can conclude when the ratioof T, B cell is extremely low, CD3^-CD56^dimCD16⁺NK cell subsets in mediating GVLhas played an important role in early reconstruction stage after unrelated umbilical cordblood transplantation.