Cytidine deaminase activity as a measure of acute inflammation in rheumatoid arthritis.

Abstract

SUMMARY Cytidine deaminase (CD), a cytoplasmic enzyme, is thought to leak out of damaged cells and can be measured in fluids by a simple biochemical assay. This study has shown that serum CD activity is raised in rheumatoid arthritis (RA) compared with osteoarthritis (OA). Synovial fluid (SF) CD activity was always less than the corresponding serum activity (mean SF/serum ratio=0-6) in OA but up to 22 times greater than the corresponding serum activity in RA (mean SF/serum ratio= 13-1), suggesting CD production in inflammatory joints. Evidence to support the SF neutrophil as a cell of CD origin is provided by the CD gradient running from cells to SF to synovium. The close correlation between SF CD activity and neutrophil count (r=0-93) indicates that SF CD activity is an accurate measure of acute synovial inflammation. Weak correlation of serum CD activity with erythrocyte sedimentation rate (ESR) (r=0 44) and Creactive protein (CRP) (r=0-49) implies that CD estimations supply different though related information about rheumatoid disease activity. We suggest that CD released from damaged neutrophils diffuses from all inflamed joints into the blood, so that serum CD activity may provide an integrated measure of joint inflammation more specific than traditional measures such as the ESR.

Serum Adenosine Deaminase and Cytidine Deaminase Activities in Patients with Systemic Lupus Erythematosus

“…Recent studies have focused on isoenzyme pattern of ADA, which has two isoenzymes: ADA-1 and ADA-2. CD catalyses the hydrolytic deamination of cytidine, deoxycytidine and their analogues (9,10). Although its tissue source is not yet known, it is suggested that the monocyte-macrophage cell system is a major source of ADA-2 in humans (8).…”

Can cytidine deaminase be used as predictive biomarker for gemcitabine toxicity and response?

“…Since cytidine analogues are widely used, a simple test would be preferred. Moreover, inflammation results in a large variation of CDA activity, leading to the hypothesis that CDA may be a marker of rheumatoid arthritis . Because the variation induced by inflammation may be larger than that caused by a genotype, a phenotypic assay measuring enzyme activity to evaluate fluctuations in CDA activity would be preferable over a genomic assay.…”

Adenosine Deaminase Activity in Joint Effusions

“…In fact, measurement of the ADA activity in peripheral blood cells from normal blood donors shows similar values in lymphocytes and granulocytes (18). In chronic inflammation of the joint, inflammatory cell turnover probably is reflected in certain synovial fluid enzyme levels, such as lysozyme (19), lactofenin (20), immunoreactive vasoactive intestinal peptide (21), elastase (22) and cytidine deaminase (23). These enzyme activities correlate with certain cell components of the local inflammatory response.…”