In this study of patients with RA and knee synovitis, major findings were that S-calprotectin correlated better with markers of disease activity than SF-calprotectin, and a novel finding that S-calprotectin showed a highly significant and strong correlation with inflammatory markers in the anti-CCP2 positive subgroup of patients, stronger than in the anti-CCP2 negative subgroup. This evidence concerns the gene AGBL2 and rheumatoid arthritis.