Nonoxidative Fungicidal Mechanisms of Mammalian Granulocytes: Demonstration of Components with Candidacidal Activity in Human, Rabbit, and Guinea Pig Leukocytes

Granulocytes from the peripheral blood of normal subjects and a patient with hereditary myeloperoxidase deficiency were homogenized in 0.34 M sucrose. A granule-rich fraction, prepared by sedimentation at 27,000 x g for 20 min, contained components that killed C. parapsilosis in vitro. These were extractable with 0.01 M citric acid and were shown by micropreparative polyacrylamide electrophoresis to be multiple. The candidacidal activity of these neutrophil components was heat stable and they were somewhat more active at pH 5.0 than at pH 7.0. When rabbit or guinea pig heterophils were obtained from sterile peritoneal exudates and similarly fractionated, they also were found to contain components that killed C. parapsilosis in vitro. These were primarily associated with a group of lysosomal cationic proteins lacking direct counterpart in human neutrophils. Among the candidacidal components of the human neutrophil was a protein, more cationic than lysozyme, that exhibited naphthol-ASD acetate esterase activity.