Systemic T cell response to Toxoplasma gondii antigen in patients with ocular toxoplasmosis

Analysis of systemic cellular response to Toxoplasma antigen in patients with ocular toxoplasmosis.

Activated (CD25(+)) T cells were detected by flow cytometry after a 7-day culture of whole blood from patients with ocular (n = 16) or asymptomatic (n = 14) toxoplasmosis, and controls (n = 10), in the presence of soluble Toxoplasma antigen (ST-Ag). Interferon (IFN)-gamma, interleukin (IL) 4, and IL-10 were measured in culture supernatants by enzyme-linked immunosorbent assay.

Higher percentages of CD25(+) T cells were detected in ST-Ag-activated cultures from Toxoplasma-infected patients, with or without ocular lesions (37.0 +/- 19.1% or 41.1 +/- 19.3%, respectively) than from controls (3.2 +/- 1.2%) (P < 0.0001). Differences were not statistically significant between asymptomatic and ocular toxoplasmosis (P > 0.4) or among congenital, acquired, and undetermined ocular toxoplasmosis (P > 0.2). Higher levels of IFN-gamma were detected in ST-Ag-stimulated blood cultures from infected patients than in those from controls (P < 0.0001), with no difference between patients with asymptomatic or ocular toxoplasmosis (P > 0.05). IL-10 was detected only in activated culture supernatants from three patients with ocular toxoplasmosis and two patients with asymptomatic toxoplasmosis. IL-4 was never produced in ST-Ag-activated cultures.

Systemic cellular response to ST-Ag does not differ between the patients with ocular and asymptomatic toxoplasmosis with regard to activation markers and type 1 cytokine production.