Determination of anti-CCP antibody by biotin-streptavidin amplified ELISA system

Objective To develop a highly sensitive,specific and simple enzyme linked immunosorbent assay(ELISA)for determination of anti-cyclic citrullinated peptide(CCP)antibody.Methods By using the pattern of streptavidin pre-immobilization and conjugation with biotin-CCP(SA/Bio-CCP),the experimental conditions of ELISA for anti-CCP antibody were optimized and its methodology and results of clinical application were evaluated.Results The diagnostic sensitivity,specificity,positive/negative predictive value,positive/negative likelihood ratio and Youden's index in rheumatoid arthritis(RA)patients were 69.4%,96.8%,89.1%/94.1%,19.28/0.317 and 0.658 respectively.Parallel investigation showed that absorbance and cut-off ratio of anti-CCP antibody was significantly correlated with Euroimmun Kit(n=61,R=0.92531,P0.001).Among 168 samples,60 positive and 105 negative results were consistent by both assays,and the consistent rate was up to 98.2%.A high consistency with Euroimmun assay(Kappa=0.961,P0.001)was shown.Area under receiver operative characteristic curve,i.e.AUCROC was 0.901,which suggested that the diagnostic accuracy of anti-CCP antibody tested by the established method was up to a higher level.Of 13 early RA cases,10 cases were positive(positive rate:76.9%).No association between anti-CCP antibody and clinical symptoms,activity index(ESR)and rheumatoid factor level in RA patients.Conclusion The amplified system of biotin-streptavidin was successfully applied in ELISA for determination of anti-CCP antibody.Its results were sensitive,specific and reliable,so it is suitable for diagnosis of RA in routine laboratories.