THE RELATIONSHIP BETWEEN URINARY NEOPTERIN LEVELS AND DISEASE ACTIVITY IN PATIENTS WITH UVEITIS

Abstract

Abstract: : Purpose: Neopterin (NP) is a pteridine derivative which is produced in monocytes/macrophages primarily upon stimulation with interferon–γ. NP is an immunologic marker for the activation of the cell–mediated immune system and it is found to be elevated in body fluids in conditions like infections and malignancies. NP concentrations not only reflect the activation of cellular immunity but also allow monitoring and prognosis of disease progression. In this study, we aimed to evaluate the relationship between urinary neopterin (NP) levels and disease activity in patients with uveitis. Methods: Urine samples from 31 active uveitis patients (17 Behcet’s Disease, 10 non–specific posterior uveitis, 2 anterior uveitis, and 2 sympathetic ophthalmia) and from 13 inactive uveitis patients (6 Behcet’s Disease, 4 non–specific posterior uveitis, 2 Vogt–Koyanagi–Harada syndrome, and 1 sympathetic oftalmia) were compared with urine samples from 27 age– and sex–matched healthy controls. Presence or absence of uveitis activity was determined by clinical examination and fundus florescein angiography findings. From the patients initial daily urination samples were collected and kept at –70 ^oC until testing. Samples were measured by with high–performance liquid chromatography and urinary neopterin measurements were expressed as the ratio of urinary NP to urinary creatinine. The findings were analyzed using Kruskal–Wallis test and Mann–Whitney U–test with Bonferroni correction. Results: The differences between active uveitis, inactive uveitis and control groups were highly statistically significant (p < 0.001, Kruskall–Wallis test). Mean urinary NP levels in patients with active uveitis and control subjects were 260±97 and 174±38 µmol/mol creatinine respectively. The difference between these groups was statistically significant (p < 0.001). Mean urinary NP level in inactive uveitis patients was 154±62 µmol/mol creatinine and the difference between active and inactive uveitis patients was statistically significant (p < 0.001). The difference between inactive patients and the control group was not significant. Conclusions: Urinary NP levels were profoundly increased in active uveitis patients. NP appears useful as a biochemical activity marker to confirm the clinical findings in uveitis patients. Further studies are needed to evaluate the predictive value of NP as a relapse indicator in inactive uveitis patients.

Keywords: uveitis–clinical/animal model • inflammation • clinical laboratory testing