Although there was no change in lesion size or parasite numbers in the skin at week 2 after infection (Figure 5J), we found significantly lower frequencies of GzmB-expressing CD8+ T cells in Cybb–/– mice than in WT (Figure 5K), forging a link between NADPH oxidase–dependent ROS production and the development of pathogenic CD8+ T cells in cutaneous leishmaniasis lesions. Here, FMO5 is linked to cutaneous leishmaniasis.