FIG. 3.

Effect of the addition of l-tryptophan (L-Trp) on the intracellular replication of T. gondii tachyzoites in 2C4 cells activated with rIFN-γ (900 IU/ml) and/or rTNF-α (60 IU/ml). Tryptophan was added to the culture medium at a final concentration of 1 mM immediately after the parasite infection, and the replication was evaluated 24 h later. An asterisk indicates a result statistically different from the control group (P < 0.05). Results indicate the means ± the standard errors of the means from three independent experiments done in duplicate.