Abstract: An efficient expression system of human soluble transferrin sTfR antigen was constructed by various strategies and the stable rabbit polyclonal antibody was obtained by immunization. High sensitivity in vitro detection kit was developed using sTfR antigen and antibody. A suitable expression system was chosen to express sTfR in human embryonic kidney cells 293 (HEK293), and the expression amount of sTfR was 0.52 mg/mL. To further improve the expression level of sTfR, the CMV promoter and the albumin signal peptide were added, leading to a significant increase in the amount of sTfR (0.86 mg/mL). High titer of rabbit sTfR polyclonal antibody was obtained using 0.3 mg sTfR antigen for the fifth immunization. When using sTfR kit to analysis human serum samples, the kit developed in this work was credible and stable. The development of sTfR kit and raw materials had significantly reduced the production cost. This work also offered an efficient approach for the development of other in vitro diagnostic reagents.

Key words: serum transferrin receptor, recombinant expression, polyclonal antibody, in vitro diagnosis, immunity