Anti-Toxoplasma gondii secretory IgA in tears of patients with ocular toxoplasmosis: immunodiagnostic validation by ELISA

Toxoplasma gondii causes posterior uveitis and the specific diagnosis is based on clinical criteria. The presence of anti-T. gondii secretory IgA (sIgA) antibodies in patients' tears has been reported and an association was found between ocular toxoplasmosis and the anti-T. gondii sIgA isotype in Brazilian patients. The purpose of this study was to provide an objective validation of the published ELISA test for determining the presence of anti-T. gondii sIgA in the tears of individuals with ocular toxoplasmosis. Tears from 156 patients with active posterior uveitis were analysed; 82 of them presented characteristics of ocular toxoplasmosis (standard lesion) and 74 patients presented uveitis due to other aetiologies. Cases of active posterior uveitis were considered standard when a new inflammatory focus satellite to old retinochoroidal scars was observed. The determination of anti-T. gondii sIgA was made using an ELISA test with crude tachyzoite antigenic extracts. Tears were collected without previous stimulation. Detection of sIgA showed 65.9 percent sensitivity (95 percent CI = 54.5-74.4), 71.6 percent specificity (95 percent CI = 59.8-81.2), a positive predictive value of 72 percent (95 percent CI = 60.3-81.5) and a negative predictive value of 65.4 percent (95 percent CI = 54.0-75.4). sIgA reactivity was higher in the tears of patients with active posterior uveitis due to T. gondii (p < 0.05). The test is useful for differentiating active posterior uveitis due to toxoplasmosis from uveitis caused by other diseases.

Características clínicas de 64 indivíduos portadores de uveítis posterior activa presumiblemente toxoplásmica en Pernambuco / Clinical characteristics of 64 individuals carrying active posterior presumptively toxoplasmic uveitis, in Pernambuco

OBJETIVO: Describir características clínicas de uveítis posterior activa, presumiblemente por Toxoplasma gondii (UPAPT) en portadores de lesión típica. Estudio tranversal. MÉTODOS: 64 portadores de UPAPT con retinocorroiditis cicatrizada y lesión satélite activa, mayores de 10 años, inmunocompetentes, examinados en Permambuco, Brazil. Se analizó: sexo, edad, color de la piel, procedencia, uveítis anteriores, agudeza visual, presión ocular y exámen ocular. RESULTADOS: Masculino en 52 por ciento. Edad media 29 años (±10,87). Piel blanca en 68,8 por ciento. Domicilio en la área metropolitana en 80,4 por ciento. Primer episodio de uveítis en 56,2 por ciento. Media de visión en ojo afectado 20/200. Presión ocular media 14,5 mmHg (±7,64) en ojo afectado. Conjuntiva hiperemiada en 29,7 por ciento. Alteraciones corneales en 51,6 por ciento. Células en el humor acuoso en 67,2 por ciento. Sinéquias posteriores en 6,2 por ciento. Compromiso vítreo en 100 por ciento. Vasculitis retiniana en 45,3 por ciento. Lesiones localizads en la zona I de Holland en 42,2 por ciento, siendo de tamaño igual o mayor de un diámetro de disco en 90,6 por ciento. Neuritis en 28,2 por ciento. CONCLUSIÓN: UPAPT afecta adultos jóvenes, siendo el síntoma principal la disminución de la visión. Presión ocular media normal. Compromiso vítreo en todos los casos. Com mayor frequencia las lesiones fueron mayores de un diámetro de disco localizadas en la zona I de Holland.

PURPOSE: To describe clinical characteristics of posterior active uveitis presumptively by Toxoplasma gondii (PAUPT) in patients with typical lesion. Tranversal study. METHODS: Sixty-four patients with retinochoroiditis scatter and active satellite lesions examined in Pernambuco, Brazil. All were older than 10 years and immunocompetent. Gender, age, skin color, and residence were recorded. Previous uveitis, visual accuracy, intraocular pressure (IOP), and ocular examination were analyzed. RESULTS: 52 percent were males, most of them with white skin (68.8 percent). Mean age 29 years (±10.87). Eighty-four percent of the patients lived in the metropolitan area. 56.2 percent were having the first episode of uveitis. In the damaged eye, visual accuracy mean was 20/200, IOP mean 14.5 mmHg (±64). Hyperemia of the conjunctiva was observed in 29.7 percent of the patients and alterations of the cornea in 51.6 percent. There were cells in the aqueous humor in 62.7 percent. 6.2 percent had posterior synechiae. All had vitreous damage and 45.3 percent retinal vasculitis. In 42.2 percent of the patients, lesions were located in zone I of Holland and 90.6 percent had the size of one discus diameter or greater. Neuritis was observed in 28.2 percent. Uveitis was more frequent in the right eye (54.7 percent). CONCLUSION: PAUPT affects young people and the main symptom was reduction of visual acuity. IOP mean was normal. Alterations of the vitreous were observed in all cases. Injuries were equal to one discus diameter or greater and located in zone I of Holland.

Value of estimating intraocular antiboddy production in diagnosi of typical and atypical lesions of ocular toxoplasmosis

Serum and aqueous humor [AH] samples were collected from 45 patients: 20 with typically active or reactivated retinal lesions of Toxoplasma [group I], 16 with atypical lesions [group II] and 9 with old quiescent scars [group III]. Also, serum and AH samples were collected from 10 patients with chronic toxoplasmosis without any ocular manifestation [group IV]. T. gondii specific IgG, IgA and IgM antibodies were measured by ELISA in AH and serum and the intraocular [local] antibody production was determined by calculating Goldman- Witmer coefficient [GWC]. IgG antibodies were the only class detected in all sera of patients with ocular and nonocular toxoplasmosis. An intraocular IgG antibody synthesis was confirmed in 95% and 37.5% of patients with typical [group I] and atypical [group II] posterior uveitis, respectively, and in no one of either patients with quiescent scars [group III] or the ophthalmologically free patients [group IV]. As regards the typical active lesions, the sensitivity of the IgG assay [95%] was higher than that of IgA [60%] and IgM [5%] assays