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

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.

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.

Constant domain of heavy chain (C(H)) and light chain (C(L)) of AbCD71 were in the human Cgamma family and human Ckappa 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 mononuclear 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.

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.