Olopatadine inhibits TNF alpha release from human conjunctival mast cells

Background: Tumor necrosis factor-alpha (TNF alpha) release likely plays a crucial role in allergic ocular inflammation via increasing ICAM-1 on epith elial cells and triggering other proinflammatory events. The immediate and prolonged release of TNF alpha from human conjunctival mast cells in respon se to allergen challenge is potentially an important target for therapeutic intervention, yet the effect of ocular anti-allergic agents on this proces s has not been examined. Olopatadine (Patanol) is a clinically effective du al-action ophthalmic anti-allergic agent that has been shown to inhibit mas t cell histamine, tryptase, and PGD(2) release in vitro and promote decreas ed H-1 receptor binding activity in vitro and functional H-1 receptor antag onism in vivo. Objective: To investigate the effect of olopatadine on TNF alpha release fr om anti-IgE antibody challenged purified human conjunctival mast cells. Methods: Human conjunctival mast cells were purified (>95%) from cadaveric tissues using a procedure combining enzymatic digestion and Percoll gradien t centrifugation. These cells were incubated with olopatadine for 30 minute s then challenged with anti-IgE antibody for 90 minutes. Supernatants were analyzed for TNF alpha. Results: Purified human conjunctival mast cells responded to anti-IgE antib ody challenge with TNF alpha release in a concentration dependent manner (o ptimum concentration was 10 mu g/mL). Olopatadine pre-incubation resulted i n a dose-dependent decrease in anti-IgE antibody mediated TNF alpha release (IC50 = 13.1 mu M). At a concentration of 3 mM olopatadine reduced TNF alp ha release to the level of unchallenged controls. Conclusion: Olopatadine inhibited anti-IgE antibody-mediated release of TNF alpha from human conjunctival mast cells. This effect could contribute to the long duration of anti-allergic activity reported for the drug.