Chicken neutrophils: oxidative metabolism in phagocytic cells devoid of myeloperoxidase.

Abstract

Polymorphonuclear leukocytes isolated from chicken peritoneal exudates have been found to catalyze cyanide-insensitive stimulation of respiration and the hexose monophosphate shunt upon exposure to heat-inactivated Staphylococcus aureus. However, there was no demonstrable formate oxidation concomitant with phagocytosis in either the presence or absence of exogenous catalase. Moreover, chicken polymorphonuclear leukocytes failed to oxidize scopoletin concomitant with phagocytosis in the presence of horseradish peroxidase. While oxygen uptake was increased 2-to 3fold by the stimulus of phagocytosis, the oxidation of [1-'4Clglucose was increased approximately 20-fold. The cells contain two mechanisms, a glutathione reductase-glutathione peroxidase system and an NADPH-NAD+ transhydrogenase, each of which is present in sufficient capacity to accommodate the enhanced shunt activity. Although chicken polymorphonuclear leukocytes were found to possess a substantial capacity to catalyze the cyanide-insensitive oxidation of either NADH or NADPH, the total or specific activities of such processes were not demonstrably affected by phagocytosis. The myeloperoxidase (MPO)-hydrogen peroxide-halogen system is deemed an important bactericidal mechanism of polymorphonuclear leukocytes (PMN) (1). However, in a few reported cases, individuals have been found to have PMN deficient in MPO although they are healthy and free of bacterial infections (2, 3). Previous investigations by one of the authors has established that the PMN of chickens are naturally devoid of MPO although they are quite capable of lethal activity against a variety of microorganisms (4, 5). As potential bactericidal mechanisms, the chicken PMN contain a family of six low-molecular-weight cationic proteins and two structurally distinct lysozymes (6). Because it is devoid of MPO, we have considered the possibility that chicken PMN provide a naturally occurring counterpart of the MPO-deficient PMN of humans. In order to further explore this possibility, we have evaluated certain of the parameters of oxidative metabolism in chicken PMN. Such a study might pinpoint fundamental similarities or differences in the biochemical characteristics of the PMN of chickens and humans, thereby adding to an increased understanding of the bactericidal mechanisms of both cell types. EXPERIMENTAL Chicken PMN were elicited and harvested from the peritoneal cavity in essentially the same fashion and purity as described previously (4, 5 to the incubation system at a level of 105 cpm per flask; the specific activities were 45, 53.7, and 24.5 mCi/mmol, respectively. H'4COONa was prepared for use by acidification and evacuation (followed by subsequent neutralization) to remove any contaminating 14CO2. Evolved '4CG2 was collected on Fiberglas paper containing 0.2 ml of 20% KOH, and the radioactivity was determined in a toluene-Triton

The NADPH oxidase of professional phagocytes—prototype of the NOX electron transport chain systems

“…However, the advent of automated differential leukocyte counting machines, where the identification of neutrophils was dependent upon a peroxidase stain, revealed that about 1 in 2000 of the general population is MPO deficient without any undue predisposition to infection [215], and the neutrophils of birds do not contain MPO [235]. …”

The Effect of 5-Fluorouracil Treatment of Chicks: A Cell Depletion Model for the Study of Avian Polymorphonuclear Leukocytes and Natural Host Defenses

“…These phagocytic cells are recruited to the site of an infection by both bacterial components and host inflammatory mediators (Schiffmann et al, 1975;Fernandez et al, 1978;Ford Hutchinson et al, 1980;Lee and Snyder, 1985;Ming et al, 1987;Baggiolini et al, 1989). At the site of the infection, heterophils respond to the infectious agent by phagocytizing and killing the pathogen in many cases (Penniall and Spitznagel, 1975;Powell, 1987a,b).…”

“…Most of the data describing and defining the role of avian heterophils in natural resistance to microbes have been obtained from in vitro studies (Brune et al, 1972;Topp and Carlson, 1972;Penniall and Spitznagel, 1975;Hamilton, 1979,1980;Thies et al, 1983;Andreasen et al, 1990;Latimer et al, 1990;Cordon et al, 1991). However, in order to study the contribution of heterophils as effectors in natural host defenses, direct in vivo experimental approaches must be developed.…”

The molecular and cellular pathology of Chronic Granulomatous Disease

“…Myeloperoxidase reacts with 0 2 -in the phagocytic vacuole and has the ability to degrade H202 to HzO through a catalase-like mechanism, and may only halogenate at low concentrations of peroxide. It is certainly not essential for immunity to infection because large numbers of symptomless subjects have been identified whose cells are completely devoid of this enzyme [79], and it is not found in neutrophils of chickens [80].…”