Serum uric acid levels and leukocyte nitric oxide production in multiple sclerosis patients outside relapses

Background: A number of studies found that patients with multiple sclerosis (MS) have low serum levels of uric acid. It is unclear whether this represents a primary deficit or secondary effect. Uric acid is a scavenger of peroxynitrite, which is the product of nitric oxide (NO) and superoxide. Because peripheral blood leukocyte NO production and NO metabolites in serum are raised in MS patients, associations might be expected between serum uric acid levels and peripheral NO production. Methods: Serum levels of uric acid and NO production by peripheral blood leukocytes were measured in 60 patients with MS without a relapse in the past 3 months, and 30 age- and sex-matched healthy controls. Uric acid was determined with the uricase PAP method, and NO production was assayed by measuring nitrite concentration in supernatants of lysed leukocytes. Results: Serum uric acid levels were not different between MS patients and controls. Compared to controls, patients with MS had significantly higher peripheral blood leukocytes nitrite concentrations (p < 0.001). There was no correlation between leukocyte nitrite concentration and serum uric acid levels. Conclusions: Our findings suggest that in MS patients there is no primary deficit in serum uric acid. NO production by peripheral blood leukocytes is increased, but there is no association with serum uric acid levels. (c) 2005 Elsevier B.V. All rights reserved.