Semi-quantitative ELISA for the detection of IgC class of autoantibodies specified to cyclic citrullinated peptide (CCP) in human serum (including Serum Separator Tubes) or plasma (EDTA, lithium heparin, or sodium citrate) This method calculates concentration values using a Four Parameter Logistic Fit (4PL). Optional dilution factor values are applied to the final concentration. Unknown samples which are outside the range of the calibrators are highlighted in yellow.