Antigen-binding characteristics of AbCD71 and its inhibitory effect on PHA-induced lymphoproliferation

Aim: To investigate the anti-lymphoproliferative effect of the prepared recombinant chimeric human/murine anti-cluster of differentiation(CD) 71 monoclonal antibody (AbCD71), which is composed of mouse-derived, antigen-binding variable regions and human-derived constant regions. Methods: After plasmids construction and transfection, the expression of AbCD71 in the transfectoma supernatant was determined by the sandwich ELISA. Indirect immunofluorescence assay was used to measure the antigen-binding characteristic and the percent CD71-expressed peripheral blood mononuclear cells (PBMC). The antibodies were purified from the ascites via diethylaminoethyl(DEAE)-Sephadex A-50 chromatography 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 )of AbCD71 were in the human C γ family and human C κ family, respectively. AbCD71 could 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. There was no statistical difference when compared with original murine mAb. Conclusion: The AbCD71 is a promising immunosuppressant. Our approach to blocking CD71 with the chimeric human/murine mAb provides a novel strategy for prolonging allograft survival.