Monocytes are the major source of active caspase-1 during malaria.

<p>PBMCs were obtained from either <i>P. vivax</i> or <i>P. falciparum</i> malaria patients as well as from healthy donors. (<b>A</b>) The gate was set based on monocytes profile in PBMCs from <i>P. vivax</i> infected patients. PBMCs were stained with anti-CD14 and anti-CD16 antibodies to determine the presence of different monocyte subsets. These cells were gated based on FSC and SSC to avoid neutrophil contamination. When the CD14^dimCD16⁺ gate was moved down in PBMCs from healthy donors or from malaria patients after treatment, we did not detect any active caspase-1. The bar graphs show the flow cytometry analysis of PBMCs from five <i>P. vivax</i> infected subjects before and after malaria treatment primaquine and chloroquine, as well as eight healthy donors. To determine the median fluorescence intensity (MFI) and frequency of (CD14⁺CD16⁻) and (CD14^dimCD16⁺) that are active caspase-1, we used the FLICA assay. (<b>B – top panel</b>) Active caspase-1 (p10) was detected in lysates of PBMCs from <i>P. vivax</i> or (<b>C – top panel</b>) <i>P. falciparum</i> infected individuals by Western blot. (<b>B and C – bottom panel</b>) PBMCs were stimulated with LPS (100 ng/ml) for 24 hours, and levels of IL-1β assessed in the culture supernatants by ELISA. Significant differences are *<i>p</i><<i>0.05</i> and **<i>p<0.005</i> as indicated by the unpaired <i>t</i> test with Welch correction or Mann-Whitney test when a normality test failed.