Figure 3

Correlation of anti-chondroitin sulphate C IgM levels with the disease and activity markers in rheumatoid arthritis. (a) Box plots of anti-chondroitin sulphate (CS) C IgM concentrations groups of controls and patients with rheumatoid arthritis (RA). The logarithm of the anti-CSC IgM concentration is plotted. The lines inside the boxes denote the medians. The boxes mark the interval between the 25th and 75th percentiles. The ends of the vertical lines or whiskers indicate the minimum and maximum data values, unless outliers are present in which case the whiskers extend to a maximum of 1.5 times the interquartile range. The difference between the controls (n = 55) and RA patients (n = 66) is statistically significant (p < 0.02, F-test). (b) Box plots of anti-CSC IgM concentrations in groups of controls and the patients with RA. Patients are stratified according to disease activitity scores (DAS) 28. Patients classified to DAS 1 group (n = 6) have significantly higher anti-CSC IgM concentrations compared with controls and to patients in the DAS 2 (n = 22) and 3 (n = 18) categories. No other significant differences have been found (p < 0.05, post-hoc Tukey's test). Result suggests that anti-CSC IgM is not a disease, but a state dependent marker. (c) Comparison of C-reactive protein (CRP) levels in patients according to their DAS scores. On the vertical axis the logarithm of CRP concentration is plotted. The only significant difference was found between groups DAS 1 and 3 (p < 0.05, post-hoc Tukey's test). (d) Box plots of anti-CSC IgM concentrations in groups of controls and patients with RA. Patients were stratified according to their CRP values into three subgroups: those having low, moderate or high CRP values (n = 17, n = 16 and n = 16, respectively). The anti-CSC IgM titre decreases when CRP concentration increases; the difference between the low and high CRP group is statistically significant (p < 0.05, post-hoc Tukey's test).