The effect of cytokines on the replication of T-gondii within rat retinal vascular endothelial cells

Toxoplasma gondii infection of the eye can result in a recurrent necrotising retinochoroiditis (TR) which may lead to a permanent loss of visual acuity. The mechanisms responsible for the control of TR within the retina are unknown. The aim of this study was to examine the effects of cytokines on the replication of T. gondii RH strain tachyzoites within mt retinal vascular endothelial (rRVE) cells. Pretreatment of rRVE with IFN gamma, TNF or IL-1 beta resulted in a significant decrease in T. gondii replication from day 2 onwards. There was no significant difference in nitric oxide (NO) production by IFN gamma, TNF or IL-1 beta treated rRVE as compared to controls at any time point. By comparison, the addition of L-tryptophan to IFN gamma treated cultures significantly restored T. gondii replication from 48 h post inoculation. Thus, IFN gamma, TNF and IL-1 beta can significantly inhibit the replication of T. gondii within rRVE. However, this inhibition appears to be independent of NO production. L-tryptophan catabolism may have a role in IFN gamma mediated inhibition of T. gondii replication in rRVE cells. (C) 2000 Elsevier Science B.V. All rights reserved.