Clinical value of second- and third-generation assays of anti-cyclic citrullinated peptide antibodies in rheumatoid arthritis

The role of anti-cyclic citrullinated peptide (CCP) antibodies in early detection of rheumatoid arthritis: an overview of the INOVA Diagnostics, Inc. QUANTA Lite CCP assays

INTRODUCTION

Rheumatoid arthritis (RA) is an autoimmune disease characterized by chronic inflammation and the presence of self-reactive autoantibodies. Since the discovery of anti-cyclic citrullinated peptide (anti-CCP) antibodies, several assays have been developed to measure these autoantibodies in RA patients. The first-generation kit offered high specificity, but sensitivity was low. The second-generation IgG anti-CCP antibody assay (CCP2) offered the same high specificity, with greatly improved sensitivity for RA. INOVA Diagnostics, Inc. offers, in addition to CCP2, a third-generation assay with higher sensitivity compared with CCP2 and also a combined IgG/IgA anti-CCP antibody assay.

AREAS COVERED

The review covers the use of INOVA Diagnostics, Inc. multiple anti-CCP antibody assays in early detection of RA, while also comparing these assays with other commercially available methods of measuring anti-CCP antibodies. While most of the review focuses on the significance of these autoantibodies in adult RA patients, their role in juvenile idiopathic arthritis is also discussed.

EXPERT OPINION

Detection of anti-CCP antibodies has emerged as one of the most important disease markers in RA patients. Several methods are available to measure anti-CCP antibodies, and isotyping and identification of citrullination targets are now the next step in further characterizing these autoantibodies.

Anti-citrullinated peptide antibody assays and their role in the diagnosis of rheumatoid arthritis

Increasingly, assays for the detection of anti-citrullinated peptide antibodies (ACPA) are used in RA diagnosis. This review summarizes the biologic basis and development of ACPA assays, available ACPA assays and their performance characteristics, and diagnostic properties of ACPA alone and compared to rheumatoid factor (RF) in early RA. We also review correlations, precision, costs and cost-effectiveness, availability, stability and reproducibility of the available assays. Taken together, data indicate that ACPA has a higher specificity than RF for early RA, good predictive validity, high sensitivity, apparent cost-effectiveness and good stability and reproducibility. Given its superior performance characteristics and increasing availability, ACPA is emerging as the most useful single assay for the diagnosis of RA.