Fig 6. Control of intracellular parasite burden by IFNγ-LPS and splenic CD4⁺ T cell-mediated macrophage activation.

(A) Hamster bone marrow-derived macrophages were primed with IFNγ before being triggered with LPS and infected with L. donovani. Parasite burden and macrophage activation were determined by measuring mRNA expression (real time RT-PCR) of Leishmania 18s, iNOS and Arg1, respectively. (B) Bone marrow-derived macrophages from uninfected hamsters were infected in vitro with luciferase-transfected L. donovani promastigotes and co-cultured with CD4⁺ T cells purified from uninfected or 28-day infected hamsters for 48 hours. The intracellular parasite burden in CD4⁺ T cell-macrophage co-cultures was determined using relative luminescent unit values and is presented as the percent increase or decrease from the baseline (1 hr) parasite burden (100%) for each group. (C) iNOS and Arg1 mRNA expression in CD4⁺ T cell-macrophage co-cultures was determined by real time RT-PCR at baseline (1 hr) and 48 hours later. Results are expressed as a relative fold change in comparison to the initial time point of each treatment group. All data shown is representative of at least 2 independent experiments with 6 replicates per group. ND = Not Detected. **p<0.01, ***p<0.001, ****p<0.0001.