The Role Of Donor γδt Cells And Host "Unlicensed" Ly49~+NK Cells In Graft-Versus-Host Disease

Part I:The role of donor γ δ T cells in acute GVHD post allogeneic hematopoietic stem cell transplantationObjective:To investigate the role of donor y8T cells in acute GVHD post allogeneic hematopoietic stem cell transplantation.Methods:BALB/c(H2Kd)recipient mice were lethally irradiated with 750cGy total body irradiation(TBI)and infused with 1 ×107 C57BL/6(H2Kb)bone marrow(BM)cells and 5×106 splenocytes 4 hours later.Mice were monitored daily for survival,body weight and clinical score.FACS analysis was performed to examine the immune cell subsets in spleen,liver,lung and small intestine on day 14 after allogeneic hematopoietic stem cell transplantation.γδT,Vγ1 and Vy4 cells were cultured in vitro and adoptive transferred into the recipient mice on day 0 after HSCT.Mice were monitored daily for survival,body weight and clinical score.FACS analysis was performed to examine the immune cell subsets in spleen,liver,lung and small intestine on day 14 after allogeneic hematopoietic stem cell transplantation.Results:The absence of donor derived γδT cells promoted aGVHD after allogeneic hematopoietic stem cell by increasing the infiltration of DC and T cells in target organs.Adoptive transfer of Vy4 cells alleviated aGVHD by inhibiting T cell activation and promoting MDSC infiltration.Conclusion:Donor derived γδT cells exhibited a protective role in the aGVHD after allogeneic hematopoietic stem cell transplantation.Vy4 T cell subset exhibited a critical function in the prevention of aGVHD.Part II:The role of host "unlicensed" Ly49+ NK cells in chronic GVHDObjective:To investigate the role of host "licensed" and "unlicensed"Ly49+ NK cells in cGVHD.Methods:Murine cGVHD model was established by injecting 1.5 ×107 DBA/2(H2Kd)donor mice CD4+ T cells into the B6D2F1(H2Kb/d)recipient mice through tail vein.Murine urine and blood were collected every two weeks.BCA and ELISA were performed to detect urine protein and anti-ds DNA antibodies respectively.FACS analysis was performed to examine the immune cell subsets in the spleen at Week 2 and Week 8 after the model was established.10 weeks later,kidney was removed and H&E staining was applied to determine the pathological condition.Results:Host NK cells protected mouse from cGVHD.Early and continuously depletion of host NK cells induced the secretion of anti-dsDNA antibody and increased CD4+ T cells and B cells infiltration as well as activation.Depletion of host "licensed"Ly49C/I+ NK cell subset caused severed kidney damage while depletion of host"unlicensed" Ly49G2+ NK cell subset had protective effect on the development of cGVHD.Conclusion:Host NK cells exhibited a protective role in the development of cGVHD.Continuously depletion of host NK cell accelerated anti-dsDNA antibodies induced cGVHD.Depletion of host "licensed" Ly49C/I+ NK cell subset aggravated cGVHD,while depletion of host "unlicensed"Ly49G2+ NK cell subset had protective effect on the development of cGVHD.