Purpose: To quantify the presence of the proinflammatory cytokine tumor necrosis factor-alpha (TNF-alpha) in allergic conjunctivitis.
Materials and methods: Tears and peripheral blood samples were collected from patients with seasonal allergic conjunctivitis (SAC, n=6), vernal keratoconjunctivitis (VKC, n=12), and normal subjects (CT, n=12). From an additional six nonactive allergic patients, tears were collected before and after specific conjunctival allergen challenge (CAC). Upper tarsal conjunctival biopsies were obtained from five CT and five VKC patients. TNF-alpha in tears was measured by enzyme-linked immunoassay and identified in tissues by immunohistochemistry.
Results: Tear TNF-alpha levels in VKC patients were significantly increased compared to CT (p=0.03), and were significantly correlated with the severity of the disease. No differences were found between SAC and CT tear samples. TNF-alpha serum levels were higher in VKC than CT, however, this difference was not statistically significant. After CAC, tear TNF-alpha levels were found increased in only one of six patients. In VKC tissues, TNF-alpha positive cells were significantly increased compared to CT (p=0.03).
Conclusions: TNF-alpha may have a significant role in severe forms of allergic conjunctivitis.