NET-dependent inhibition of C albicans growth is compromised in MPO-deficient neutrophils. Neutrophils from a healthy donor and a completely MPO-deficient donor (donor 1) were stimulated to make NETs using glucose oxidase for 2 hours or were left unstimulated. After NET formation, cells were left untreated or cytochalasin D was added to prevent phagocytic killing by neutrophils that had not made NETs. The yeast form of C albicans was added to the cells, and fungal growth was measured after 10 hours using XTT, a chromogenic metabolic substrate. Measurements were normalized to growth of C albicans in the absence of neutrophils. Control neutrophils efficiently made NETs and restricted fungal growth both in the presence and in the absence of cytochalasin D. MPO-deficient neutrophils did not restrict fungal growth in the presence of cytochalasin D.