Figure 1.

Detection and enrichment of autoantibodies in rheumatoid arthritis (RA) synovial extracts. Tissues were obtained by arthroplasty or arthroscopic shaver biopsy, and serum and synovial extracts were analyzed by enzyme-linked immunosorbent assay for antibodies of interest and albumin. (a) Individual levels of RF-IgM, anti-CCP IgG, and anti-tetanus IgG in extracts from osteoarthritis (OA) (n = 12, autoantibodies; n = 11, anti-tetanus) and RA (n = 21, autoantibodies; n = 14, anti-tetanus) synovial tissue, normalized to total protein concentration. Limits of detection are 4 (RF-IgM), 10 (anti-CCP IgG), and 0.3 (anti-tetanus IgG). Serum-normalized levels of (b) RF-IgM and anti-CCP IgG in RA synovial extracts (n = 11) and (c) anti-tetanus IgG in OA (n = 6) and RA (n = 9) synovial extracts. In the box (interquartile range, IQR) and whisker (maximum and minimum) plots, the horizontal line inside the box denotes median and the unfilled circles denote outliers outside IQR ± 1.5 × IQR. The asterisk denotes P = 0.019 by Wilcoxon sign rank test to 1 (no enrichment) for anti-CCP IgG (a), and the indicated P value was determined by Wilcoxon rank sum test between OA and RA for anti-tetanus IgG (b). The value for RF-IgM was not significantly above 1 (P = 0.32). anti-CCP, anti-cyclic citrullinated peptide; RF-IgM, rheumatoid factor of the IgM subtype; SSI, synovial/serum index.

Rosengren et al. Arthritis Research & Therapy 2008 10:R105   doi:10.1186/ar2497
Download authors' original image