Evidence for a Compartmentalized B Cell Response as Characterized by IgG Epitope Specificity in Human Ocular Toxoplasmosis

Abstract

Infectious agents in the eye induce both a local and a systemic humoral immune response. Previously, differences in Ag recognition were observed between systemic and ocular derived IgG of patients with ocular toxoplasmosis. This finding implied a nonrandom distribution of IgG-producing B cells in the inflamed eye. In the present study, we compared the intraocular and systemic B cell responses of patients with ocular toxoplasmosis to a single Toxoplasma gondii Ag. Two series of C-terminally deleted recombinant T. gondii GRA-2 proteins were constructed to delineate IgG B cell epitopes of paired ocular and serum samples. Differences in epitope region recognition between the ocular and systemic compartment were detected in 9 of 13 patients. The difference in distribution of GRA-2 epitopes between paired samples is indicative of a local GRA-2 specific B cell population functionally different from the systemic GRA-2-specific B cell population. Our results suggest a selective activation of a subset of B cells locally in nonlymphoid tissue.

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

“…The result might also reflect lesion size, which tends to be larger in individuals with acquired ocular toxoplasmosis. However, the findings are also compatible with different modes of infection handling (Klaren and Peek, 2001;Vallochi et al, 2001;Yamamoto et al, 2000) and a local or systemic site of infectious activity (Figueroa et al, 2000).…”

Immunopathology in ocular toxoplasmosis: facts and clues

“…Moreover, at least in recurrences of OT, the immune response is a highly localized and compartmentalized event, which is confined to B-cell activity and thus to lymphocyte homing (Klaren & Peek 2001). Only an analysis of the specificity of the T-cell infiltrate or of the immunoglobulins that are deposited within the diseased tissues can furnish conclusive evidence of an autoimmune component ).…”

Peptide Microarray Analysis ofIn Silico-Predicted Epitopes for Serological Diagnosis of Toxoplasma gondii Infection in Humans

“…Several experimental approaches have been used to identify protein regions and epitopes suitable for the serological diagnosis of T. gondii, including phage display of cDNA libraries, epitope mapping, and reactivity with monoclonal antibodies (5,11,26,29,41,49). For this study, a bioinformatic approach was used for in silico prediction of 20 B-cell linear epitopes on the T. gondii antigenic proteins GRA1, GRA2, GRA4, and MIC3.…”