Tg IgG-: samples from patients who were seronegative for (n?=?250). CONCLUSION: We detected higher levels of anti-retina antibodies in uveitis patients and in a small fraction of asymptomatic patients with chronic toxoplasmosis. The presence of anti-retina antibodies in sera might be a marker of eye disease in asymptomatic patients, Rgs2 especially when whole human retina extract is used in a solid-phase ELISA. infection is usually asymptomatic in humans, and persistent infection with the cyst form of this parasite is controlled by the host immune system. However, in fetuses and immunosuppressed patients (such as AIDS patients or organ transplant recipients), the parasite becomes activated and causes life-threatening disease.9 A specific retina involvement may be present in up to 20% of all infected individuals, regardless of their immune status. 10 Toxoplasmosis is the most frequent cause of posterior uveitis in the USA and Brazil, and it is associated with visual impairment and blindness. The diagnosis is usually based on characteristic fundoscopy findings and the clinical presentation; the disease is usually progressive and recurrent, and it can cause severe morbidity. These outcomes occur despite the availability of an effective treatment based on pyrimethamine, which is an anti-parasitic drug that is associated with anti-inflammatory drugs such as corticosteroids.11 In the eye, the primary target tissue for ocular toxoplasmosis is the neural retina, which displays a surrounding, intense granulomatous reaction with numerous intracellular parasite cysts.12 Free tachyzoites and cysts are also observed within retina pigment epithelium (RPE) cells.13 Ocular reactions also involve necrosis of the retina and RPE, subretinal and choroidal neovascularization, and focal inflammation.14 The inflammatory processes Indapamide (Lozol) that are associated with retina infection by may damage Bruch’s membrane, which results in a disruption of the choroidoretinal interface.4 uveitis can present the same autoimmune response as SO and VKH: a disruption of the parasite cysts that exposes the retina antigens. When central vision is threatened, ocular toxoplasmosis is treated with specific antibiotics together with corticosteroids, which suggests that the host immune response plays an active role in the disease process. In ocular toxoplasmosis, the involvement of the eye and inadequate autoimmune responses of memory cells to retina antigens in the blood have been reported previously,10,14 but few studies have reported a high frequency Indapamide (Lozol) of retina autoantibodies titers in this condition.15,16 Furthermore, another group detected robust levels of cellular responses against retina antigens in the blood of ocular toxoplasmosis patients10. Alternatively, cross-reactive antigens could be encoded and produced by the infectious agent, which could induce autoimmunity Indapamide (Lozol) via Indapamide (Lozol) a cross-reactive immune response of antigen mimicry, which has also been reported for American trypanosomiasis.17 Autoimmunity that is induced by mechanical antigen exposure or by cross-reactive antibody production cannot be distinguished in established usual experimental models with active or chronic infection because both processes can occur concomitantly. To search for anti-retina antibodies that could serve as markers for eye disease, we investigated the serum levels of anti-retina antibodies in asymptomatic anti-seropositive and seronegative uveitis patients who were diagnosed with Indapamide (Lozol) or without ocular toxoplasmosis. Whole human retina extracts, S-antigens and IRBP were analyzed using an optimized ELISA. MATERIALS AND METHODS Serum samples Five hundred serum samples were recovered from storage at the Protozoology Laboratory of IMTSP; these samples were previously used in epidemiological studies of the seroprevalence of toxoplasmosis in S?o Paulo State. The samples had been collected from healthy individuals with no symptoms at the time of blood collection, and according to defined patterns for routine ELISA and IFA anti-IgG serology, 250 samples were positive (Tg IgG+ group), and 250 samples were negative (Tg IgG- group). We prospectively collected 80 serum samples from patients who were diagnosed with uveitis and undergoing treatment at the Uveitis Service in the Department of Ophthalmology at the Hospital das Clinicas, University of S?o Paulo, School of Medicine. Thirty uveitis patients were diagnosed with ocular toxoplasmosis based on a.