Development and validation of immunogenicity methods for detecting telitacicept
Objective:To establish a bridging enzyme-linked immunosorbent assay(ELISA)method for the de-termination of anti-drug antibody(ADA)and a competitive ELISA method for the determination of neutralizing antibody(NAb)in cynomolgus monkey serum,and to conduct methodological validation.Methods:The steps of bridging ELISA method were as follows:the 96-well plates were precoated with telitacicept(RC1 8)which could combine with anti-RC18 antibody in the samples to form a complex,then were sequentially added biotinylated RC18(Biotin-RC18),horseradish peroxidase conjugated streptavidin(SA-HRP),and tetramethylbenzidine(TMB)substrate solution for color development.After terminating the reaction,the absorbance was read at a wavelength of 450 nm/630 nm on an ELISA reader.The procedures of competitive ELISA method were as follows:the 96-well plates were precoated with B-cell activation factor of the TNF family(BAFF)or a proliferation in-ducing ligand(APRIL)protein and then were added the samples which was pre-mixed with Biotin-RC18 to form BAFF or APRIL anti-RC18-antibody and Biotin-RC18 complex.SA-HRP and TMB substrate solution for color development were added sequentially.After terminating the reaction,the absorbance was read at an ELISA reader with dual wave length.Results:The precision of linear range of bridging ELISA method was less than 12.32%,the sensitivity was 50 ng·mL-1,the critical threshold of screening was 0.937,and the critical threshold of confirmation was 23.62%.The precision of the linear range of competitive ELISA method was less than 20%,the sensitivity was 312.50 ng·mL-1,and the threshold for determining the activity of NAb against the target BAFF and APRIL was 0.79 and 0.69,respectively.On BAFF and the method of research targets re-spectively can tolerate 2.5 μg·mL-1 and 5 μg·mL-1 RC18 in serum.Conclution:The results of method vali-dation indicate that both bridging ELISA and competitive ELISA meet the requirements of preelinical immunoge-nicity studies of biological products,and can be used for analysis of the concentrations of ADA and NAb in cvno-molgus monkey serum.