Infection with Toxoplasma gondii does not Alter TNFα and IL-6 Secretion by A human Astrocytoma Cell Line

The secretion of tumour necrosis factor-alpha (TNFalpha), interleukin-1alpha (IL-alpha) and interleukin-6 (IL-6) by a human astrocytoma cell fine was studied 1 h, 3 h, 6 h and 24 h after infection with tachyzoites from three Toxoplasma gondii strains (virulent, RH; cystogentc, 76K and Prugniaud strains). The astrocytoma cell fine constitutively secreted TNFalpha and IL-6, but no IL-1alpha. A positive control was obtained by stimulation with phorbol esters inducing a significant increase (p < 0.05) in TNFalpha and IL- 6 secretion but not in IL-1alpha, while lipopolysaccharide (alone and after priming), interferon gamma, ionophore A 23187 and sera positive to T. gondii did not induce any increase in cytokine levels. None of the tachyzoites, whatever their virulence, induced a significant increase in cytokine production at any time in the study. Tachyzoites did not inhibit the secretion induced by phorbol esters.