Chloride is the predominant anion that regulates phagosomal oxidant production in PMN phagosomes. NADPH oxidase transfers electrons into the phagosomal lumen, thereby creating a transmembrane potential that activates voltage-gated proton channels, such as Hv1, to conduct an influx of protons. In addition, the ATP-driven proton pump vacuolar-type ATPase (V-ATPase) actively pumps protons in the same direction. Other cations such as K⁺, Na⁺, and Ca²⁺ can be transported into phagosomes via monovalent or divalent cation/H⁺ exchangers, or K⁺/Cl^‒ symporter. To counterbalance the influx of the cations, Cl^‒ is transported through chloride channels, including CFTR, CaCC, and voltage-gated ClCs.