Aqueous Levels of Interleukin-6 in Patients with Uveitis

Abstract

Purpose: : To determine if aqueous levels of interleukin-6 (IL-6), a proinflammatory cytokine, correlate with clinical classifications and inflammation severity.

Methods: : A retrospective chart review was conducted to identify patients who had aqueous humor specimens analyzed at the National Eye Institute from 2000 - 2010. Clinical data included visual acuity, activity of the anterior chamber and vitreous and recent systemic or local medications. Follow up visits were reviewed to determine the clinical course and diagnosis. All aqueous samples were assessed for IL-6 levels. Depending on the specimen volume, additional cytokines, cytology, molecular analyses, and cultures were also performed.

Results: : Sufficient data was available for 35 aqueous samples from 32 patients with uveitis. 23 samples (66%) had detectable IL-6 levels. Higher IL-6 levels (>100 pg/mL) were likely to be associated with a higher grade of anterior chamber inflammation (P=0.0064). Patients on systemic corticosteroids or other immunomodulatory medications were statistically less likely to have detectable IL-6 levels (P=0.0045). The highest levels of IL-6 (≥55,496 pg/mL) occurred in aqueous from patients who were confirmed to have bacterial endophthalmitis.Of the 29 cases with cytology, lymphocytes were the most frequently found (17/29) and polymorphonuclear neutrophils were the fewest (8/17). IL-6 levels were higher (>500pg/mL) if numerous leukocytes were also noted on cytology (P=0.0067). Although there was a trend, there was no statistically significant correlation between vitritis and positive IL-6 levels.

Conclusions: : Eyes with severe anterior chamber inflammatory activity have significantly elevated aqueous IL-6 levels. Infectious uveitis yields the highest aqueous IL-6 levels. Systemic corticosteroids or immunosuppressive medications seem to suppress aqueous IL-6; therefore, aqueous IL-6 levels greater than 100 pg/mL in the presence of immunosuppressive therapy may be of particular clinical relevance.

Keywords: aqueous • cytokines/chemokines • inflammation