Elevated nitric oxide production in patients with primary Sjogren's syndrome

Nitric oxide (NO) production is elevated in patients with inflammatory diso rders. We have previously shown increased NO production in patients with rh eumatoid arhtritis and systemic lupus erythematosus. In this stud!: we used nitrite and citrulline levels as surrogate markers of NO production in pat ients with primary Sjogren's syndrome (SS) and measured their levels by spe ctrophotometry. Fifteen patients and 15 age- and sex-matched controls were studied. Mean nitrite levels in patients were 582.3 +/- 208.3 nmol/ml, but those in controls were significantly lower, at 203.2 +/- 106.9 nmol/ml (p<0 .001). Citrulline levels were 2820.4 +/- 933.9 nmol/ml in patients and were significantly higher than 217.4 +/- 144.8 nmol/ml, the levels in controls (p<0.0001). Mean levels of both nitrite and citrulline were significantly h igher in patients with arthritis than in those who had no joint manifestati ons (p<0.05). There was no correlation between NO production and other vari ables, such as age, disease duration, drug therapy and antinuclear antibodi es or rheumatoid factor positivity. Increased NO production may be partly a reflection of the presence of arthritis in five patients. It is concluded that there is increased NO production in patients with primary SS, especial ly if they have associated arthritis.