Objective: To produce 60-kDa recombinant Sjőren's syndrome antigen A (SSA-60) by gene engineering and establish and evaluate the performance of a magnetic microparticle chemiluminescence quantitative method for detecting anti-SSA-60 antibody in sera.
Methods: Recombinant antigen was prepared by gene recombination technology and purified by high affinity Ni2+ resin. The immunogenicity of the recombinant antigen was verified in immunized BALB/c female mice, and the immune reactivity of our recombinant antigen was assessed using the enzyme-linked immunosorbent assay (ELISA) method. With this recombinant antigen, a specific magnetic microparticles chemiluminescence assay (MMC assay) was developed and performed using various parameters.
Results: The inner-group difference among high, medium and low density sera mixtures was 7.65%, 2.24%, and 2.47%, respectively, and the inter-group precision rate was 8.25%, 6.26%, and 4.87%, respectively, using the MMC assay. The low detection limit was 1.36 relative unit per milliliter (Ru/mL), and the quantitative limit was 4.48 Ru/mL. The linear range of this method was 2-400 Ru/mL, which is wider than that of ELISA. The standard error (SE) of the differences was 31.3 between the two methods. Good correlation (y = 1.04x - 7.86, R2 = 0.979, P < 0.05) and high agreement (Kappa = 0.95) were noted between the two methods.
Conclusions: These data show that the MMC assay provides high sensitivity and specificity and a wider linear range in anti-SSA-60 aab detection and fairly good agreement and correlation between the MMC assay and ELISA. The MMC assay has potential in rapid, high-throughput, quantitative and automated autoimmune antibody testing.
Keywords: Agreement; Automated assay; Chemiluminescence; Immunoassay; Recombinant SSA antigen.
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