Summary:In the present study, phagocytosis and the oxidative metabolism of neutrophil granulocytes from five clinically healthy persons with different degrees of myeloperoxidase deficiency were investigated and compared to those of normal persons. The identification of individuals with myeloperoxidase deficiency was performed with the Bayer/Technicon H3 blood cell counter, which differentiates the leukocytes by measuring the peroxidase activity. Neutrophils of three out of five investigated myeloperoxidase deficient persons showed extremly low peroxidase indices (-53 and lower), but only the neutrophils of one person totally lacked myeloperoxidase. This was demonstrated by comparing myeloperoxidase mass concentration measured with an enzyme immunoassay, lack of HOC1 production, and was further confirmed by measuring luminol-and lucigenin-enhanced chemiluminescence. Characteristically, myeloperoxidase deficient granulocytes showed a strikingly decreased luminol-enhanced chemiluminescence while the lucigenin-enhanced chemiluminescence was significantly increased compared to normal granulocytes. Although there is a DNA sequence homology of about 70%, the activity of peroxidase in eosinophils was not affected in any myeloperoxidase deficient person investigated. Moreover, a person with a very rare defect of eosinophil peroxidase had completely normal myeloperoxidase activity. The lack of myeloperoxidase activity is compensated for by an increased phagocytic activity, an increased production of Superoxide anion (lucigeninchemiluminescence) and probably by an alternative metabolism of H 2 O 2 ; since persons lacking myeloperoxidase activity do not normally suffer from severe infections, H 2 O 2 is obviously metabolized to other reactive oxygen substrates than HOC1, e. g. to OH-radicals.

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Chronic granulomatous disease (CGD) is an inherited primary immunodeficiency characterized by phagocytes devoid of a functioning nicotinamide adenine dinucleotide phosphate (NADPH) oxidase. The failure of CGD phagocytes to produce reactive oxygen species (ROS) results in a marked increase in the susceptibility of affected patients to life-threatening bacterial and fungal infections. This study investigated whether loading of CGD phagocytes with glucose oxidase (GO)-containing liposomes (GOLs) could restore cellular production of bactericidal ROS (eg, H 2 O 2 and HOCl) in vitro. Results indicate that GO encapsulated in liposomes enabled NADPH oxidase-deficient phagocytes to use H 2 O 2 for the production of highly bactericidal HOCl. The intracellular colocalization of bacteria and liposomes (or liposome-derived ferritin) was demonstrated by confocal laser microscopy and electron microscopy. After uptake of GOLs (approximately 0.2 U/mL at 1 mM total lipid concentration, size approximately 180 nm), CGD granulocytes produced HOCl levels comparable to those of normal phagocytes. Remarkably, after treatment with GOLs, CGD phagocytes killed Staphylococcus aureus as efficiently as normal granulocytes. Moreover, treated cells retained sufficient motility toward chemotactic stimuli as measured by chemotaxis assay. Side effects were evaluated by measuring the H 2 O 2 concentrations and the production of methemoglobin in whole blood. These studies revealed that H 2 O 2 produced by GOLs was degraded immediately by the antioxidative capacity of whole blood. Elevated methemoglobin levels were observed only after application of extremely high amounts of GOLs (2 U/mL). In summary, the application of negatively charged GOLs might provide a novel effective approach in the treatment of patients with CGD at high risk for lifethreatening infections. IntroductionChronic granulomatous disease (CGD) is a primary immunodeficiency with an incidence of 1:1 000 000 to 1:250 000. 1 It is an inherited disorder (X chromosomal or autosomal recessive) of the phagocyte system. 2 Phagocytes (granulocytes and monocytes) of patients with CGD lack a functional nicotinamide adenine dinucleotide phosphate (NADPH) oxidase and are not able to produce reactive oxygen species (ROS), necessary for microbial killing. 3 The disease is therefore dominated by high susceptibility to a variety of bacteria and fungi, especially those with catalase activity. 4 Therapy and prevention of infections include the life-long administration of antibiotics and antimycotics, and in severe cases, the transfusion of allogeneic granulocytes to provide the patient with functioning phagocytes. 5 In recent years the idea of encapsulating drugs such as antibiotics or cytostatics into liposomal carriers has become more feasible. 6 Phagocytes tend to take up conventional liposomes very easily. 7 This uptake is often a disadvantage in the use of liposomes for many medical applications and clinical trials because of rapid elimination of the encapsulated drug. We developed glucose oxid...

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