Aim:To investigate the anti-lymphoproliferative effect of the prepared recombi-nant chimeric human/murine anti-cluster of differentiation(CD) 71 monoclonalantibody (AbCD71),which is composed of mouse-derived,antigen-binding vari-able regions and human-derived constant regions.Methods:After plasmids con-struction and transfection,the expression of AbCD71 in the transfectoma super-natant was determined by the sandwich ELISA.Indirect immunofluorescence as-say was used to measure the antigen-binding characteristic and the percent CD71-expressed peripheral blood mononuclear cells (PBMC).The antibodies were puri-fied from the ascites via diethylaminoethyl(DEAE)-Sephadex A-50 chromatogra-phy and then identified by SDS-PAGE.At last,inhibitory effect of AbCD71 onPHA-induced PBMC proliferation was calculated by methyl thiazolyl tetrazolium(MTT) assay.Results:Constant domain of heavy chain(C_H) and light chain(C_L)ofAbCD71 were in the human C_γ family and human C_K family,respectively.AbCD71could compete with its original murine mAb to bind with CD71-positive humanleukemia cell line CEM cells.AbCD71 could inhibit the peripheral blood mono-nuclear cell proliferation induced by phytohemagglutinin(PHA) in vitro in a dose-dependent manner,especially at time-points 0 and 12 h after induction.There wasno statistical difference when compared with original murine mAb.Conclusion:The AbCD71 is a promising immunosuppressant.Our approach to blocking CD71with the chimeric human/murine mAb provides a novel strategy for prolongingallograft survival. Aim: To investigate the anti-lymphoproliferative effect of the prepared recombi-nant chimeric human / murine anti-cluster of differentiation (CD) 71 monoclonalantibody (AbCD71), which is composed of mouse-derived, antigen- binding vari-able regions and human -derived constant regions. Methods: After plasmids con-struction and transfection, the expression of AbCD71 in the transfectoma super-natant was determined by the sandwich ELISA. Indirect immunofluorescence as-say was used to measure the antigen-binding characteristic and the percent CD71 -expressed peripheral blood mononuclear cells (PBMC). The antibodies were puri-fied from the ascites via diethylaminoethyl (DEAE) -Sephadex A-50 chromatogra-phy and then identified by SDS-PAGE. At last, inhibitory effect of AbCD71 on PHA-induced PBMC proliferation was calculated by methyl thiazolyl tetrazolium (MTT) assay. Results: Constant domain of heavy chain (C_H) and light chain (C_L) ofAbCD71 were in the human C_γ family and human C_K family, respectively.AbCD71coul d compete with its original murine mAb to bind with CD71-positive human leukemia cell line CEM cells. AbCD71 could inhibit the peripheral blood mono-nuclear cell proliferation induced by phytohemagglutinin (PHA) in vitro in a dose-dependent manner, especially at time-points 0 and 12 h after induction. Where was statistical difference when compared with original murine mAb. Conflusion: The AbCD71 is a promising immunosuppressant. Our approach to blocking CD71 with the chimeric human / murine mAb provides a novel strategy for prolongallograft survival.