Salivary exoglycosidases in the detection of early onset of salivary gland involvement in rheumatoid arthritis.

Introduction: The aim of the present study was to evaluate the possibility of making use of the specific activity of N-acetyl-β-hexosaminidase, its isoenzymes and β-glucuronidase--potential indicators of salivary gland damage--in the detection of early onset of salivary gland impairment in RA, which is also demonstrated by xerostomia.

Material/methods: For this purpose RA xerostomic salivary patients (unstimulated salivary flow >0.1 mL/min) were compared with RA xerostomic hyposalivary patients (unstimulated salivary flow ≤0.1 mL/min), RA patients without xerostomia (unstimulated salivary flow >0.1 mL/min) and generally healthy controls (unstimulated salivary flow >0.1 mL/min, without xerostomia). Salivary N-acetyl-β-hexosaminidase, its isoenzymes A and B, and β-glucuronidase specific activity were determined according to the Marciniak et al. method. The protein content in the unstimulated saliva was determined by the bicinchoninic acid method.

Results: In xerostomic rheumatoid arthritis patients, the specific activity of salivary β-glucuronidase and isoenzyme A was significantly higher than in the healthy controls but the specific activity of salivary N-acetyl-β-hexosaminidase, its isoenzyme B and β-glucuronidase was significantly lower than in xerostomic hyposalivary rheumatoid arthritis patients.

Conclusions: We suggest a simple, safe and cheap method for the determination of exoglycosidases as a useful tool for the diagnosis of early stages of salivary gland involvement in rheumatoid arthritis.