Specific antibody levels in the aqueous humor and serum of two distinct populations of patients with ocular toxoplasmosis.

The population of Erechim, Southern Brazil, is characterized by a high incidence of ocular toxoplasmosis, which is presumed to be of acquired origin. We wished to compare the local specific humoral immune response of individuals from this region with that of Swiss patients suffering from the same disease. Paired samples of aqueous humor and serum were withdrawn from 27 Brazilian and 50 Swiss patients presenting consecutively with active ocular toxoplasmosis. The total and specific levels of IgG in each of these were determined. The populations did not differ with respect either to age or sex. The serum levels of total IgG in Brazilian (10.8 g/l) and Swiss patients (11.1 g/l) were similar (p = 0.499), but the aqueous humor ones were higher in the former group (95 vs. 20 mg/l; p = 0.0001). The systemic and local levels of specific IgG were likewise higher in Brazilian patients [206 i.u. vs. 72 i.u. (p = 0.001) and 14 i.u. vs. 4 i.u. (p = 0.005), respectively] and the number of individuals without detectable levels of local specific IgG was correspondingly lower (11% vs. 54%; p = 0.0005). The Goldmann-Witmer coefficient (an index of local specific antibody production) did not differ between Brazilian and Swiss patients (2.1 vs. 0.08, respectively; p = 0.107). Our findings are indicative of a more pronounced uveovascular barrier breakdown in Brazilians than in Swiss patients with active ocular toxoplasmosis. That the systemic and local specific immune response is weaker in Swiss than in Brazilian patients has not been hitherto documented. This finding may reflect differences in the immunological handling of the infection.

Aqueous humor and serum immunoblotting for immunoglobulin types G, A, M, and E in cases of human ocular toxoplasmosis.

The purpose of this study was to compare the local and systemic Toxoplasma-specific humoral immune responses in individuals with ocular toxoplasmosis (OT). To this end, paired aqueous humor and serum samples from 46 individuals with active OT and from 30 individuals without inflammatory eye disease (controls) were analyzed by immunoblotting for anti-Toxoplasma immunoglobulin G (IgG), IgA, IgM, and IgE directed against 20- to 120-kDa antigens. The presence in the aqueous humor of a unique band, or of at least three bands that were at least three times more intense in aqueous humor than in serum, was taken as evidence of local antibody production. IgG bands were detected in 98% of the aqueous humor samples, while IgA bands were detected in 76%, IgM bands were detected in 8%, and IgE bands were not detected in any. Evidence of local production of specific antibodies was found in 32 cases (70%) (IgG in 23 [50%]; IgA in 16 [35%]). In 10 instances (22%), routine laboratory tests were not indicative of OT. In 14 cases (30%), no local antibody production was detected by immunoblotting; 3 of these cases yielded evidence of local antibody production according to the Goldmann-Witmer coefficient. Local antibody production was revealed for 7 of the 30 controls (23%). Hence, the sensitivity of immunoblotting for IgG and IgA is 70%, and the specificity is 77%. We conclude that immunoblotting for local specific IgG and IgA supports the clinical diagnosis of OT in 70% of cases. In 22% of these, the diagnosis is not confirmed by other laboratory tests. Hence, immunoblotting increases the sensitivity of routine laboratory tests and should be considered for samples that register negative by such tests.

Vertical transmission of toxoplasmosis from a chronically infected immunocompetent woman.

We report the vertical transmission of congenital toxoplasmosis from a chronically infected immunocompetent woman to her child. On the background of published knowledge in this field, vertical transmission must have developed after maternal reinfection or reactivation of the preexisting disease.