Increased frequency of anti-retina antibodies in asymptomatic patients with chronic t. gondii infection

PURPOSE: To search for anti-retina antibodies that serve as markers for eye disease in uveitis. MATERIALS AND METHODS: Stored sera from patients with uveitis, ocular toxoplasmosis (n = 30) and non-infectious, immune-mediated uveitis (n = 50) and from asymptomatic individuals who were positive (n = 250) and negative (n = 250) for anti-Toxoplasma antibodies were tested. Serum anti-retina IgG was detected by an optimized ELISA using a solid-phase whole human retina extract, bovine S-antigen or interphotoreceptor retinoid-binding protein. RESULTS: Uveitis patients showed a higher mean reactivity to whole human retina extract, interphotoreceptor retinoid-binding protein and S-antigen in comparison to the asymptomatic population. These findings were independent of the uveitis origin and allowed the determination of the lower anti-retina antibody cut-off for the three antigens. Asymptomatic anti-Toxoplasma serum-positive individuals showed a higher frequency of antihuman whole retina extract antibodies in comparison to asymptomatic anti-Toxoplasma serum-negative patients. The bovine S-antigen and interphotoreceptor retinoid-binding protein ELISAs also showed a higher mean reactivity in the uveitis groups compared to the asymptomatic group, but the observed reactivities were lower and overlapped without discrimination. 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, especially when whole human retina extract is used in a solid-phase ELISA

Experimental and serological evidence of humoral autoimmune response against retina in Toxoplasma gondii uveitis

A toxoplasmose ocular é atribuída ao parasita, mas a auto-imunidade pode participar do processo. Soros humanos com IgG positiva para T. gondii mostraram níveis altos de IgG anti-retina para diferentes antígenos, se comparados com soros negativos para T. gondii, uveítes de outras origens também tiveram títulos elevados. Hamsters imunizados e/ou infectados não mostraram estes anticorpos sem mimetismo antigênico. A retinocoroidite por Toxoplasma induz resposta humoral auto-imune contra antígenos da retina, provavelmente piorando o efeito direto do agente. Estes anticorpos podem ser usados como marcadores de doença ocular em pacientes soropositivos para toxoplasmose pela triagem de lesão ocular.Ocular toxoplasmosis is attributed to the parasite, but autoimmunity could have a role in this process. Human sera, positive of anti-T. gondii IgG, show high levels of anti-retina IgG, measured by several antigens, as compared to T. gondii seronegative samples. Sera from patients with uveitis from other origins also had higher anti-retina abs levels. Challenged and/or immunized hamsters showed low anti-retina abs levels, without antigen mimicry. Toxoplasmic retinochoroiditis presents a humoral anti-retina abs, probably worsening the parasite direct effect. Those antibodies could be used as markers of eye involvement in toxoplasmosis seropositive patients, as a screening for eye examination