Figure 5: Prostaglandin production by L. mexicana-infected macrophages. Prostaglandins were analyzed by MS/MS assay; product scanning experiments were conducted using nitrogen as collision gas, and the collision energy was optimized for individual compounds to generate the most abundant product ions. These product ion spectra were then used to select the precursor-product ion pairs for the development of MRM assays. Deuterium-labeled prostaglandins were used as internal standards for quantitation. Graph bars are mean ± SEM of three independent experiments, and statistical analysis was done comparing, for each time, treated versus nontreated macrophages; (*) , (**) , and (***) .