Fig 4.

L. braziliensis parasites are less susceptible to IFN-γ-mediated killing by macrophages. BM-derived macrophages from WT and TLR9^−/− mice were stimulated for 24 h with IFN-γ and TNF-α, followed by infection for 2 h with L. braziliensis (Lb) or L. major (Lm) parasites. Extracellular parasites were washed away, and cells were cultured with or without IFN-γ and TNF-α for another 48 h. Coverslips were stained with Diff-Quik, and the percentage of infected macrophages (A) as well as the number of parasites per infected macrophage (B) was determined by microscopy. (C) Supernatants were collected and NO content was measured by the Griess reaction. Data shown are presented as the mean + SEM of triplicates. *, P < 0.05 (Student's t test comparing the percentages of BMMϕ infected with parasites in the presence and absence of IFN-γ and TNF-α). Data shown here are results from 1 representative experiment of 2 individual experiments.