Method Description

Cyclic Citrullinated Peptide Antibodies:

Cyclic citrullinated peptide (CCP) antibodies in serum are detected by binding to the wells of a commercial microtiter plate coated with synthetic CCP. During the first incubation, serum antibodies bind to adsorbed, solid phase CCP. The wells are then washed to remove unbound serum constituents, and horseradish peroxidase-labeled goat anti-human IgG is added. After further incubation and washing to remove unbound conjugate, substrate (3,3',5,5' tetramethylbenzidine) is added, and the mixture incubated. The reaction between enzyme and substrate is stopped, and color in the wells measured in a microtiter plate reader. The concentration of CCP antibodies is determined by comparison to a 5-point standard curve (15.6-250 U). Testing is performed on the Agility instrument by Dynex.(Package insert: Quanta Lite CCP3 IgG ELISA. INOVA Diagnostics; 02/2020)

Rheumatoid Factor:

The Roche rheumatoid factors (RF-II) assay is an immunoturbidimetric assay. Latex-bound heat-inactivated IgG (antigen) reacts with the rheumatoid factor (RF) antibodies in the sample to form antigen/antibody complexes that, following agglutination, are measured turbidimetrically. Rheumatoid factors are autoantibodies that are directed against the Fc fragment of IgG. The autoantibodies occur in all immunoglobulin classes (IgA, IgG, and IgM). The Roche RF II assay measures all 3 types of autoantibodies. However, as the IgA and IgG types typically exhibit lower concentrations, the reaction against IgM autoantibodies predominates in this assay.(Package insert: RF-II, Rheumatoid Factors II. Roche Diagnostics; V 9.0 English, 02/2020)