Value of estimating intraocular antibody production in diagnosis 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 (G.W.C.). 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 none of either patients with quiescent scars (Group III) or the ophthalmologically free patients (Group IV). As regard the typical active lesions, the sensitivity of the IgG assay (95%) was higher than that of IgA (60%) and IgM (5%) assays. Beside the conclusion that AH analysis to detect local antibody production is more reliable than the estimating of serum antibodies for the diagnosis of ocular toxoplasmosis, the detection of AH specific antibodies in 6 atypical cases, who were treated successfully by antitoxoplasmic therapy, represent a help to increase the number of uveitis cases in which specific treatment can be established.