INFECTION WITH TOXOPLASMA-GONDII DOES NOT ALTER TNF-ALPHA AND IL-6 SECRETION BY A HUMAN ASTROCYTOMA CELL-LINE

THE secretion of tumour necrosis factor-alpha (TNF alpha), interleukin -1 alpha (IL-1 alpha) and interleukin-6 (IL-6) by a human astrocytoma cell line was studied 1 h, 3 h, 6 h and 24 h after Infection with tach yzoites from three Toxoplasma gondii strains (virulent, RH; cystogenic ; 76K and Prugniaud strains). The astrocytoma tell line constitutively secreted TNF alpha and IL-6, but no IL-1 alpha. A positive control wa s obtained by stimulation with phorbol esters inducing a significant i ncrease (P < 0.05) in TNF alpha and IL-6 secretion but not in IL-1 alp ha, while lipopolysaccharide (alone and after priming), interferon gam ma, ionophore A 23187 and sera positive to T. gondii did not induce an y increase in cytokine levels. None of the tachyzoites, whatever their virulence, induced a significant increase in cytokine production at a ny time In the study. Tachyzoites did not inhibit the secretion induce d by phorbol esters.