RÉSUMÉ
@#Objective To develop and verify a reporter gene assay for the determination of antibody dependent cellular phagocytosis(ADCP)potency of Ig G2 monoclonal antibody(m Ab)against epidermal growth factor receptor(EGFR)by combining Design of Experiment(DOE)and one factor at a time(OFAT).Methods The Jurkat/NFAT-Re/FcγRⅡa stably transformed cell line was used as effector cells,while the A431 cell line as the target cells.The JMP software was used to optimize the seven key factors in the experiment by combining DOE and OFAT analysis,while the ratio of upper and lower asymptotes(D/A)was used as the statistic,and the reporter gene method was developed to evaluate the ADCP potency of Ig G2 anti-EGFR m Ab.The method was verified according to the general chapter<9401>of Chinese Pharmaco-poeia（Ⅲ/Ⅳvolume,2020 edition)and used to determine the biological potency of Ig G2 anti-EGFR m Ab injection.Results After three rounds of experiments,the reporter gene method to evaluate the ADCP potency of Ig G2 anti-EGFR m Ab was developed.The method showed a dose-response relationship and was consistent with the four-parameter regression equa-tion y=(A-D）/[1+(x/C)~B]+D.The range of seven key conditions was determined:the density of effector cells was(1.25-3.75）×10~4 cells/well,the density ratio of effector cells to target cells was 1.0-2.0,the incubation time of target cells was 20-40 min,the incubation time of administration was 15-30 min,the total time was 5.5-6.5 h,and the color time was 5-30 min with luciferase detection system(Bright-Glo)as the color agent.The method had good specificity.Six independent tests were run for the five potency levels,with the correlation coefficient r of 0.994 5 and the linear regression equation slope of 1.02.The relative potency of five potency levels respectively was(62.15±1.38)%,(78.53±2.82)%,(99.12±3.95)%,(123.27±4.59)%and(155.22±7.04)%,the range of relative biases was-2.9%-0.2%,and the range of generalized cross-validation(GCV)was 2.2%-4.6%.The method had good linearity,relative accuracy and precision in the range of 64%-156%.The mean value of the potency of IgG2 anti-EGFR m Ab in three tests was(101.5±2.8)%.Conclusion The reporter gene assay developed in this study can be used to evaluate the ADCP potency of IgG2 anti-EGFR mAb
RÉSUMÉ
ABSTRACT To seek a simple, rapid and sensitive Coprinus cinereus Peroxidase (CIP) activity assay, a convenient one-factor-at-a-time (OFAT) method and a response surface methodology (RSM) were used. The recombinant CIP expressed in Pichia pastoris was purified with the Ni-NTA spin column. Based on the results of catalytic efficiency (kcat/Km) analysis, 2,2'-azinobis (ethylbenzthiazoline -6-sulfonate) (ABTS) was selected as the optimal enzyme substrate. Results of the OFAT method showed that enzymatic reaction performed in 0.1 mol/L sodium acetate (pH 5.0) buffer in a 200-µl reaction mixture containing 0.5 mmol/L ABTS, 10 mmol/L hydrogen peroxide (H2O2), 49.7 ng CIP at 25°C gave an average CIP activity of 88 U/mL. The ABTS and H2O2 concentrations were then further optimized to improve the sensitivity of the assay. To do that, RSM was conducted through central composite design, and a reduced quadratic model with good fit regression equation was generated. ANOVA analysis of this model indicated that the concentrations of ABTS and H2O2 and their interaction had significant impact on the assay sensitivity. The optimal reaction mixture was determined to include an initial ABTS concentration of 0.82 mmol/L 49.7 ng CIP and 16.36 mmol/L H2O2, and the activity under this condition was determined to be 138.89 U/mL.