Increased synovial fluid levels of soluble CD23 are associated with an erosive status in rheumatoid arthritis (RA)

Abstract

Synovial fluid (SF) levels of soluble CD23 (sCD23) were determined in 96 patients presenting with an inflammatory knee effusion (73 with RA and 23 with reactive arthritis (ReA) serving as a control inflammatory non-erosive group) and were correlated with the degree of joint destruction, with local immune parameters (IL-1beta, IL-3, IL-4, IL-6, IL-8, IL-10, IL-12 and sCD25) and with serum markers of inflammation, C-reactive protein and erythrocyte sedimentation rate. RA patients, classified as erosive or not according to Larsen's grade, were separated as follows: (i) 13 patients with non-erosive RA; (ii) 16 RA patients with erosions in hands but not in knees, matched for disease duration with the first group; (iii) 44 RA patients with hand and knee erosions, matched with the second group for rheumatoid factor positivity but of longer disease duration. SF sCD23 levels were significantly increased in both erosive RA groups compared with non-erosive diseases, whether RA or ReA (P < 0.05), whose SF levels were not different. SF IL-10 showed a similar profile to that of SF sCD23 and was the only other parameter characteristic of erosive RA, but no direct correlation was found between the two. SF sCD23 was significantly correlated with IL-12 (r = 0.65, P = 0.0001) and sCD25 (r = 0.39, P = 0.0019) exclusively in the two erosive RA populations. In conclusion, these data showing that increased levels of sCD23 are not only found in the SF of erosive joints but also in knee SF of patients with erosive RA but without knee x-ray-diagnosed erosions suggest that this parameter might be of predictive value for joint destruction. Longitudinal studies are however needed to confirm its potential clinical interest.

Fig. 1

Synovial fluid soluble CD23 levels in RA and reactive arthritis (ReA), a control inflammatory non-erosive arthropathy. Boxes represent the interquartile range, i.e. the middle 50% of the data, between 25th and 75th quartile. Whiskers represent the 10th and 90th quartiles, and circles represent values out of this range. Asterisks indicate a significant difference versus erosive knee−/hand+ RA: *P < 0·05; ***P < 0·001 (Mann–Whitney test).

Fig. 2

Positive linear correlation between log soluble CD23 and log IL-12 in erosive knee−/hand+ RA (○) and erosive knee+/hand+ RA (•). r and P values are those obtained for the two groups studied together.

Fig. 3

Positive linear correlation between log soluble CD23 and log soluble CD25 in erosive knee−/hand+ RA (○) and erosive knee+/hand+ RA (•). r and P values are those obtained for the two groups studied together.