Analysis of Immune Privilege in Eyes with Mycobacteria tuberculosa Adjuvant-Induced Uveitis

Purpose: To examine the effects of intravitreal Mycobacteria tuberculosa adjuvant (MTA) on ocular immune privilege. Methods: MTA was injected into the vitreous cavity of BALB/c mouse eyes to induce anterior uveitis. The inflamed eyes were then examined for their capacity to afford immune privilege to injected allogeneic tumor cells and to promote anterior chamber-associated immune deviation (ACAID). Aqueous humor (AqH) was tested for IL-12 content and for its ability to inhibit T-cell activation. Results: AqH removed from MTA-inflamed eyes at 6 and 12 h contained high levels of IL-12, which then fell almost to baseline at 24 h. This is relevant to the finding that the inflamed eye failed to support ACAID induction at an early time period and then regained the ACAID-induction capability at a later time. Nonetheless, AqH removed from MTA-inflamed eyes retained its capacity to suppress T-cell activation, and MTA-inflamed eyes afforded extended survival to alloantigenic tumor cells implanted into the anterior chamber. Conclusion: Intraocular inflammation evoked by MTA causes the local accumulation of IL-12 and simultaneously robs the eye of its capacity to promote systemic immune tolerance to eye-derived antigens. However, MTA-inflamed eyes retain immune privilege, as indicated by their support of the progressive growth of allogeneic tumor cells.