A neutrophil (multi-lobed nucleus) targets three fungal conidia (grey). It performs phagocytosis, followed by phagosome/lysosome fusion. The lysosomes release their lytic enzymes, which start to attack the conidia. The pH in the phagolysosome decreases when V-ATPase (an ATP-dependent proton pump) uses ATP to import H+ ions. Meanwhile, the NADPH in the phagolysosome membrane performs an "oxidative burst," to make toxic reactive oxygen species (ROS). The conidia are destroyed through the action of lytic enzymes, acid, and ROS.