Figure 6.

Heme affects neutrophil activation profile during L. infantum infection independent of iron. Human neutrophils were infected with L. infantum (1:5) in the absence or presence of heme (30 µM) or free iron (Fe⁺², 100 µM) and co-treated with the iron chelator deferoxamine (DFO) (A) or the reactive oxygen species (ROS) scavenger dithiothreitol (DTT) (B) for 3 h. The supernatant was then replaced by Schneider’s medium and after 24 h viable promastigotes were counted as described in Section “Materials and Methods.” The numbers of viable promastigotes (×10⁴/ml) are plotted. Each point on the graph represents a donor, and the bars represent the median vales. Data were compared using the Kruskal–Wallis test with Dunn’s post-test. *p < 0.1, **p < 0.01, ***p < 0.001.