Background CD44 is a widely expressed adhesion molecule responsible for cell-cell, cell-matrix interaction and binds hyaluronan and other extracellular matrix and cell surface proteins. Binding of CD44 leads to immune mediated inflammation, target lysis and tumour dissemination. Except this constant membrane bound form a variety of isoforms are expressed. Soluble CD44 variant isoform 5 (sCD44v5) is associated with a high rate of cell division and is elevated in patients with erosive IgM rheumatoid factor positive Rheumatoid Arthritis (RA+).

Objectives To examine whether sCD44v5 correlates with inflammation and/or joint destruction in a long-term treatment of patients with RA.

Methods Serum levels of sCD44v5 were measured in 73 patients with RA according to the criteria of ACR treated in intervals in our department in the duration of 10 years using a commercially available ELISA-test, developed by Bender-Med-Systems-Vienna. The results of sCD44v5 were compared with Disease Activity Score (DAS), 28 Joint Count (28JC), 30 Swollen Joint Count (30SJC), Ritchie Index, Proximal Interphalangeal Score (PIP), Stoke Index, Larson Score, Steinbrocker Stage, C- Reactive- Protein (CRP), Erythrocyte Sedimentation Rate (ESR), rheumatoid factor (RF) and DMARD therapy.

Results We detected elevated serum levels of sCD44v5 in 50/356 measurements, with a range from 58,4 to 312,9. The mean sCD44v5 was 42,3 ng/ml. The results showed a significant correlation with RF (mean 299,4 U/ml, p < 0,001) and a weak correlation with ESR(mean 31,9 mm HG, p < 0,03)), but no correlation with CRP (mean 21,1 mg/l), DAS (mean 3,54) and other clinical scores. Furthermore we found no significant difference of sCD44v5 with different DMARD therapies.

Conclusion In our cohort sCD44v5 does not prove to be useful as predicting factor or indicator for a long-term treatment observation. Although sCD44v5 is known to be elevated in patients with rheumatoid flare such a correlation could not be shown in our study with weak to moderate inflamed patients. Soluble CD44v5 therefore seems to be elevated only in severe inflammation.

References

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