The Role Of Anti-CD146 Antibody AA98 In Acute GVHD Afterallogeneic Hematopoietic Stem Cell Transplantation

Objective:The current study attempted toevaluate the effect ofanti-CD146 antibody AA98 on acuteGraft-Versus-Host Disease(aGVHD) during allogeneic hematopoietic stem cell transplantation(allo-HSCT).Methods: TheToxinEraser Endotoxin Removal columnswere used to remove endotoxin in purified AA98 antibodies and control antibodies AA1.Theendotoxin levels of both antibodies beforeand after endotoxin removal were tested.The antibodieswhose endotoxin level was less than 10EU/mlwerethen measured for protein concentration by BCA kit.BALB/c(H2Kd) recipient mice were received 1050 cGy total body irradiation(TBI) and infused with 1×107 C57BL/6(H2Kb) bone marrow(BM) cells mixed with 5×106 whole splenocytes 4 hours later on day 0. On day 5 post of transplantation, the CD146 expression in mice organs was detected by flow cytometry.To evaluate the role of AA98 antibody in aGVHD, the host mice were randomly divided into three groups: The host mice receivedAA98(200μg each mouse)treatment, the host mice received IgG treatmentand the host mice treated with anti-CD146 antibody AA1.Clinical manifestations of aGVHD and survival were observed after allo-HSCT. The survival rate was compared by Log-rank test.Reciepient micewere sacrificed 7 days after allo-BMT, and lymphocytes were isolated fromspleen, liver, lung and small intestine. The membrane molecules and effect molecules of T cells, NK cells and myeloid lymphocytes were then measured by flowanalysis.Results: We removed the endotoxin in AA1 and AA98 antibodies effectively. The endotoxin levels were reduced within 10EU/ml.The CD146 expression in aGVHD mice organs was markedly higher than that in bone marrow transplantation control group.AA98 antibody significantly suppressed acute GVHD after alloHSCT:(1) AA98 significantly prolonged acute GVHD-related survival;(2) significantly reduced GVHD-related body weight loss;(3) and reduced aGVHD clinical scores. Flow cytometric analysis demonstratedAA98 reduced the percentage of activated T cells but not affected the infiltrationof T cells and significantly reducedtheproduction of IFN-γand TNF-α in CD4+T andCD8+T cellsin spleen and aGVHD target organs.Conclusion: AA98 significantly prolonged survival of host mice during aGVHD.The mechanism may mainly through itsinhibition of T cell activation and the inhibition of cytokine secretion of T cells in spleen and aGVHD target organs.