Transient Association of the Nicotinamide Adenine Dinucleotide Phosphate Oxidase Subunits p47phox and p67phox With Phagosomes in Neutrophils From Patients With X-Linked Chronic Granulomatous Disease

Abstract

Optimal microbicidal activity of polymorphonuclear leukocytes (PMNs) requires recruitment of a functional nicotinamide adenine dinucleotide phosphate (NADPH) oxidase to the phagosome. In this study, we used a synchronized phagocytosis assay and immunofluorescence microscopy (IFM) to examine the association of cytosolic NADPH oxidase subunits with phagosomes containing opsonized zymosan (OpZ). Ingestion of OpZ began within 30 seconds of particle binding and forming phagosomes were enriched for both F-actin and the actin-binding protein p57. NADPH oxidase subunits p47phox and p67phox were also recruited to forming phagosomes and were retained on mature phagosomes for at least 15 minutes. Colocalization of F-actin, p57, and p47phox on phagosomes was confirmed by immunoblotting. Translocation of p67phox, but not p57, to forming phagosomes was deficient in PMNs lacking p47phox. Surprisingly, we found that in PMNs from six individuals with X-linked chronic granulomatous disease (CGD), p47phox and p67phox accumulated in the periphagosomal area during ingestion of OpZ. However, in marked contrast to normal PMNs, p47phox and p67phox were shed from nascent phagosomes along with F-actin and p57 once OpZ was internalized (≈5 minutes). These data support a model in which flavocytochrome b is required for stable membrane binding of p47phox and p67phox, but not their association with the cytoskeleton or transport to the cell periphery.