Guinea Pig Polymorphonuclear Leukocytes Research Articles

Production of superoxide and hydrogen peroxide by an NADH-oxidase in guinea pig polymorphonuclear leukocytes. Modulation by nucleotides and divalent cations.

Production of superoxide and hydrogen peroxide by an NADH-oxidase in guinea pig polymorphonuclear leukocytes. Modulation by nucleotides and divalent cations.

Interrelationship between oxygen consumption, superoxide anion and hydrogen peroxide formation in phagocytosing guinea pig polymorphonuclear leucocytes

The paper presents an experimental procedure for a simultaneous assay of oxygen consumption, O2- release and H2O2 accumulation at a very early stage of the respiratory burst that is induced by phagocytosis in guinea pig polymorphonuclear leucocytes. The main findings are as follows: (a) The oxygen consumption that is measurable does not correspond to all oxygen that is reduced. The relationship between the actual oxygen consumed and the amount that is reduced depends on the fate of the intermediate products O2- and H2O2. (b) O2- is measurable extracellularly by the reduction of cytochrome c. When cytochrome c oxidizes the extracellular O2-, molecular oxygen is formed. This fact is shown by a decrease of oxygen consumption. The molar ratio between the O2- detected and the oxygen given back is 1. (c) The amount of O2- released from the cells accounts for only a small part of oxygen actually reduced. (d) H2O2 is detectable only in the presence of NaN3. In this condition almost all oxygen consumed is recovered in the form of H2O2. The molar ratio O2/H2O2 is near unity. The amount of H2O2 derived from dismutation of O2- released is only an aliquot of the total H2O2 accumulated. Thus, most of H2O2 is derived from intracellular sources. (e) In the absence of inhibitors of H2O2 degrading reactions, no detectable accumulation of peroxide occurs. Under these conditions, the main part of H2O2 formed is degraded in almost equal amount by catalase and myeloperoxidase, while only a small aliquot is degraded by NaN3 insensitive reactions.

Chemotactic effects of the complement-derived peptides C3a, C3ai and C5a (classical anaphylatoxin) on rabbit and guinea-pig polymorphonuclear leukocytes.

The complement-derived peptides C3a, C3ai and C5a (= classical anaphylatoxin) were purified from hog serum and examined for chemotactic activity on rabbit and guinea-pig polymorphonuclear leukocytes (PMN) with the Boyden chamber technique (with filters of 3,0 micrometer pore size). When media containing albumin or serum were used all peptides induced chemotaxis of both cell species. Only C3a showed a pronounced species dependence in that it was much more active on rabbit than on guinea-pig PMN. No gross differences were found between the influence of 0.5% BSA and 10% heated (56 degree, 30 min) homologous serum added to the medium. In the absence of protein chemotaxis did not occur.

DFP-sensitive polypeptides of the guinea pig peritoneal macrophage

Guinea pig peritoneal exudate macrophages were reacted with [ 3H] diisopropyl fluorophosphate (10 −7 to 10 −4 M) and subjected to sodium dodecyl sulfate-polyacrylamide disc electrophoresis and fluorography. Macrophages reacted with 10 −5 M [ 3H]diisopropyl fluorophosphate contain eight major 3H-labelled polypeptides which have apparent molecular weights of 83,000, 75,000, 63,000, 48,000, 41,000, 30,000, 26,000, and 25,000. The sensitive polypeptides were not seen when guinea pig polymorphonuclear leukocytes, lymph node lymphocytes, erythrocytes, serum or plasma were reacted with [ 3H]diisopropyl fluorophosphate, demonstrating that these components are particular to the macrophage. The finding of a large number of diisopropyl fluorophosphate-sensitive proteins associated exclusively with the macrophage supports the concept that serine esterases play a unique role in macrophage physiology.

Effect of galactose on free radical reactions of polymorphonuclear leukocytes

To account for impaired bactericidal activity of polymorphonuclear leukocytes during galactosemia, we have investigated the effects of galactose upon free radical reactions associated with the oxygen-dependent killing mechanism of guinea pig polymorphonuclear leukocytes. Millimolar levels of galactose, which are encountered in the circulation of infants with galactosemia, did not affect the chemical reaction of Superoxide anion with either ferricytochrome c or nitroblue tetrazolium. Galactose did, however, significantly inhibit the reaction of hydroxyl radical with methional, and we propose that such hydroxyl radical removal would be deleterious to normal bactericidal activity. Additional experiments demonstrated that polymorphonuclear leukocytes incubated in the presence of galactose reduced less ferricytochrome c than polymorphonuclear leukocytes incubated without galactose. These results imply that galactose impairs the cellular release of Superoxide anion, which would further disable bactericidal activity.

Different arrangements of phagolysosome membranes which depend upon the particles phagocytized: Observation with markers of the two sides of plasma membranes

Phagolysosome vesicles containing either polystyrene latex (PLP), or PLP plus bovine serum albumin (PLP-BSA), or paraffin oil emulsified with BSA (POE-BSA) were prepared from guinea pig polymorphonuclear leukocytes (gp-PMNL). They were compared using the specific markers of the two sides of the plasma membrane of gp-PMNL characterized previously [1, 2]. Anticell surface IgG (Anti-C-S IgG) which binds exclusively to the outer side of plasma membranes [1] was found to bind to the cytoplasmic side of all three types of phagolysosomes. Anti-100000 g sup IgG which binds exclusively to the cytoplasmic side of plasma membranes of gp-PMNL [1] did not bind to the cytoplasmic side of these phagolysosomes, as shown by immunoferritin technique. On the other hand, influenza virus, which is a marker of the outer surface of plasma membranes [1] bound to the cytoplasmic side of POE-BSA phagolysosomes but not PLP or PLP-BSA phagolysosomes, as demonstrated by electron microscopy. The content of myosin, another marker of the cytoplasmic side of plasma membranes [2], differed in these phagolysosomes, as shown by SDS-polyacrylamide gel electrophoresis: it was very low in PLP- and POE-BSA phagolysosomes but high in PLP-BSA phagolysosomes. Myosin was found on the cytoplasmic side of PLP-BSA phagolysosomes by the improved immunoferritin technique reported previously [3]. These phagolysosomes, containing different particles and having different arrangements of membrane components, showed different efficiencies of fusion with lysosomes. The possible mechanism of the specific fusion of phagosomes with lysosomes was discussed in relation to these different features of phagolysosomal membranes.

Effect of antimicrobial agents on guinea pig polymorphonuclear leukocytes (author's transl)

The in vitro effect of antimicrobial agents on guinea pig polymorphonuclear leukocyte (PMN) chemotaxis was studied. Antimicrobial agents investigated in this study are penicillin-G (PC G). ampicillin (ABPC), cloxacillin (MCI PC), cephalothin (CET), erythromycin (EM), gentamicin (GM), colistin (CL), chloramphenicol (CP), tetracycline (TC), sulfoisoxazole (SI) and amphotericin-B (AMPH-B) at the concentration between 0.005μg/ml and 1000μg/ml.PAN chemotzxis was strongly suppressed by almost all drugs at a very high concentration. CET, CL, SI or AMPH-B acts PMN directly and inhibits leukocyte chemotaxis without suppression of chemokinesis. Both chemokinesis and chemotaxis are suppressed by CP or TC. MCI PC or EM acts PMN as if it is one of the chemoattractants, so that each drug inhibits leukocyte chemotaxis by the mechanism of deactivation.The results are discussed with paticular emphasis on the implications to host defence mechanism.

Fundamental research for the pharmacological activity of oriental drugs. XI. Combined effects of animal-origin drugs on the inhibition of leucocyte migration and their effective components (author's transl)

Combined effect of drugs of animal origin (musk, bezoar, bufotalis) was examined by Boyden's method, using guinea pig polymorphonuclear leucocytes for inhibitory effect on leucocyte migration. A migration-inhibitory activity was found in musk, bezoar, ninhydrin reaction-positive substances musk peptide fraction (MP) extracted from musk, and smooth muscle contracting substances extracted from bezoar. MP was the most effective of substances tested. The active component of MP was determined to be a peptide from the fact that the activity was lost by tryptic hydrolysis and that the molecular weight was estimated to be about 1000, using ultrafiltration and Sephadex. The combined action of musk-bezoar was an antagonistic type. That of muskbufotalis was not observed but that of bezoar-bufotalis was a synergistic type. The apparent combined action of muskbezoar-bufotalis was not observed but interactions described above seem at least to be included.

Demonstration of myosin on the cytoplasmic side of plasma membranes of guinea pig polymorphonuclear leukocytes with immunoferritin

The heavy chain of myosin was detected in preparations of both open sheets and vesicles of plasma membranes from guinea pig polymorphonuclear leukocytes (gp-PMNL). Myosin was detected as a band on SDS-polyacrylamide gel electrophoresis with purified gp-PMNL myosin as a marker. Myosin was not removed by washing the membrane fraction with 0.6 M KCl and 0.5 mM ATP, but disappeared when open sheets of plasma membranes were trypsinized. Therefore, it seemed to be firmly bound to the membranes and at least part of it seemed to be present on the surface of the plasma membranes. Antibody against purified gp-PMNL myosin was prepared in rabbits and used to examine the location of myosin on open sheets of plasma membrane by the indirect immunoferritin technique, as improved by us [9] to remove non-specific binding. Electron microscopy showed that myosin was present exclusively on the cytoplasmic side of plasma membranes, on the opposite side to that binding influenza virus.

Binding of markers of either side of plasma membranes to the cytoplasmic side of lysosomes

The binding of markers of each side of plasma membranes of guinea pig polymorphonuclear leukocytes (gp-PMNL) to the cytoplasmic side of membranes of isolated lysosomes of gp-PMNL was studied using an improved indirect immunoferritin technique. Anti-cell surface IgG (anti-C-S IgG) which bound to the outer surface of intact cells and was eluted from a complex of cells and antibody was previously shown not to bind to the cytoplasmic side of open sheets of plasma membrane of gp-PMNL [2]. Electron microscopy using the indirect immunoferritin technique showed that this antibody bound to the cytoplasmic side of lysosomes. Non-immunized rabbit IgG did not cause binding of indirect ferritin conjugate to lysosomes. On the other hand, influenza virus, which also bound exclusively to the outer side of open sheets of plasma membrane [2], did not bind to the cytoplasmic side of lysosomes under conditions where it bound to contaminating membrane vesicles. Anti-100 000 g sup IgG which was prepared against the 100000 g sup of a gp-PMNL homogenate in 0.6 M KCl and was preabsorbed with intact cells, i.e., which did not contain antibodies against the outer side of intact cells, bound specifically to the cytoplasmic side of open sheets of plasma membrane [2]. This antibody also bound to the cytoplasmic side of lysosomes. Moreover lysosome-specific antigenicity, i.e., antigenicity that was not common to plasma membranes, was found to be present on the cytoplasmic side of lysosomes. These results show similarities in the membrane components of plasma and lysosomal membranes, but also demonstrate great topological differences between the components.

Binding of markers of either side of plasma membranes to the cytoplasmic side of paraffin oil-loaded phagolysosomes

Preparation of paraffin oil emulsified with bovine serum albumin-loaded (POE-BSA)-phagolysosomal membranes of guinea pig polymorphonuclear leukocytes (gp-PMNL) were compared with isolated plasma and lysosomal membranes, using four markers of the two sides of the plasma membranes. Electron microscopy showed that the cytoplasmic side of POE-BSA-phagolysosomes behaved like the outer side of the plasma membranes with respect to three markers. Anti-cell surface IgG (anti-C-S IgG), which was shown by our improved immunoferritin method [1] to bind exclusively to the outer surface of open sheets of plasma membranes [2] and the cytoplasmic side of lysosomes [4] and influenza virus, which binds to the outer side of plasma membranes [2] but not lysosomes [4], bound to the cytoplasmic side of (POE-BSA)-phagolysosomal membranes. The bindings of 125I-labeled anti-C-S IgG and 125I-labeled influenza virus per μmole of phospholipid in the phagolysome fraction increased in parallel with the fusion of lysosomes to phagolysosomes. Electron microscopy also showed that anti-100000 g sup IgG, which binds to the cytoplasmic side of open sheets of plasma membrane [2] and lysosomes [4], did not bind to the cytoplasmic side of phagolysosomes. Myosin, which was shown to present only on the cytoplasmic side of open sheets of plasma membrane [3] was found to be present only in low concentration in the POE-BSA-phagolysosome fraction of sodium dodecyl sulfate (SDS) polyacrylamide gel electrophoresis. These findings show that the cytoplasmic side of the phagolysosomal membrane differs from those of plasma and lysosomal membranes; it is not a mere combination of these membranes, but gives an apparently right side-out character to vesicles of plasma membrane. From these results we suggest that dynamic changes of membrane components occur during formation of phagolysomes.

Membrane transport by guinea pig peritoneal exudate leukocytes: effect of phagocytosis on hexose and amino acid transport.

Short term, carrier mediated transport of D-glucose, L-leucine and L-lysine by guinea pig peritoneal macrophages was characterized. Analysis of the amino acid transport demonstrated two-limbed double reciprocal plots suggesting two transport systems for each amino acid. The low concentration limb of the curves established a Km of 0.1 mM for L-leucine and 0.05 mM for L-lysine; Vmax values were 2.0 and 2.85 nmole/mg protein/90 seconds, respectively. Leucine and lysine were shown to be competitive inhibitors of each other. Further competition studies revealed that other amino acids also had affinity for these carriers. Amino acid transport was found to be sensitive to sulfhydryl active compounds. Colchicine treatment of peritoneal macrophages did not inhibit the transport of the amino acids tested. Preloading macrophages with latex beads or heat-killed staphylococci by phagocytosis stimulated 2-deoxy-D-glucose (2-dOG) uptake markedly, but had no measurable effect on amino acid transport. Although total transport of 2-dOG increased in post-phagocytic macrophages, the kinetics of the system were not altered significantly. The Km for both pre- and post-phagocytic transport of 2-dOG was shown to be 1.2 mM and the Vmax was shown to increase from a pre-phagocytic value of 20 nmoles/mg protein/90 seconds to a post-phagocytic 27 nmoles/mg protein/90 seconds. Phagocytosis of heat-killed staphylococci by guinea pig polymorphonuclear leukocytes (PMNs), however, did not cause an augmentation in hexose transport in the cells. The presence of colchicine during phagocytosis did not alter subsequent uptake of amino acids by the macrophages.

Ionophores stimulate prostaglandin and thromboxane biosynthesis

The role of calcium in triggering prostaglandin and thromboxane synthesis was studied in several systems with ionophores of different ion specificities. Divalent cationophore A23187 stimulates prostaglandin and thromboxane production by washed human platelets in a concentration-dependent manner (0.3-9 muM). A23187 also induces an antimycin A-insensitive burst in oxygen utilization which is partially blocked by 5 mM aspirin or 10 muM indomethacin. Under our conditions, A23187 (up to 10 muM) does not appear to damage platelet membranes since it does not cause appreciable loss of lactate dehydrogenase or beta-glucuronidase. Mono- and divalent cationophore X537A also stimulates platelet thromboxane B(2) production and oxygen utilization, but monovalent cationophores nigericin, monensin A, A204, and valinomycin have no effect. The synthesis of prostaglandins E(2), D(2), and F(2alpha) by rat renal medulla mince is stimulated by 1 and 5 muM A23187 without changes in tissue ATP content, lactate output, or K(+) efflux. X537A, monensin A, and nigericin (all 5 muM) stimulate both prostaglandin output and K(+) efflux from renal medulla, while 5 muM valinomycin or A204 has no effect on either. None of the ionophores stimulates renomedullary prostaglandin production if calcium is omitted from the incubation medium. A23187 also stimulates prostaglandin production by human lymphoma cells, rat stomach and trachea preparations, and guinea pig polymorphonuclear leukocytes. These observations suggest a major role for Ca(2+) in stimulating prostaglandin and thromboxane biosynthesis, and also indicate that prostaglandin and/or thromboxane release may partially mediate some of the previously described effects of ionophores on cells and tissues.

Selectivity of the 2-deoxyglucose transport system in human and guinea pig polymorphonuclear leukocytes.

To determine whether the deleterious action of D-galactose upon phagocyte function could be related to inhibition of glucose uptake, the properties of glucose transport were investigated by following the incorporation of [G-3H]2-deoxyglucose into human and guinea pig polymorphonuclear leukocytes (PMN). Uptake of [G-3H]2-deoxyglucose by guinea pig PMN proceeded in vitro with a Km of 1.8 mM and Vmax of 0.67 nmol/min per 10(6) cells. This system was competitively inhibited by glucose and mannose but was not significantly affected by galactose, fructose, or 3-0-methylglucose. Maximal uptake of 2-deoxyglucose occurred at 41 degrees C, and phosphorylation was necessary for its intracellular concentration. Transport of 2-deoxyglucose, although not altered by uncouplers of oxidative phosphorylation, was sensitive to inhibitors of glycolysis. Preincubation of cells with 2 mM iodoacetate for 30 min significantly reduced the uptake of 2-deoxyglucose and the intracellular levels of adenosine-5'-triphosphate without decreasing cell viability. These results indicated that uptake of 2-deoxyglucose in guinea pig PMN occurred by facilitated diffusion with subsequent phosphorylation. Similar results were obtained with PMN isolated from human peripheral blood.

The effect of 2‐deoxyglucose on guinea pig polymorphonuclear leukocyte phagocytosis

The effects of 2-deoxyglucose (DOG), an inhibitor of glycolysis, on guinea pig polymorphonuclear leukocytes (PMN) obtained from peritoneal exudates was examined. ATP levels in PMN were reduced by 40% by one hour following an incubation with 2-deoxyglucose. When complement (C3) coated 14C-staphylococcus aureus, C3 coated lipopolysaccharide-paraffin oil droplets (LPS-PO), 14C-pneumococcus opsonized with IgG, or albumin coated paraffin oil droplets opsonized with IgG were added to cell suspensions containing DOG, the phagocytizing rate was 1,310+/-55 cpm/5 X 10(6) cells/15 minutes, 6+/-2 microng paraffin oil (PO)/10(7) cells/minute, 2,250+/-175 cpm/1 X 10(6) cells/20 minutes or 0.037+/-0.01 mg PO/10(7) cells/minute compared to control values of 5,970+/-275 cpm/5 X 10(6) cells/15 minutes, 35+/-3 microng PO/10(7) cells/15 minutes, 4,510+/-200 cpm/1 X 10(6) cells/20 minutes and 0.067+/-0.01 mg PO/10(7) cells/minute. In parallel studies the phagocytic index for latex was 0.74+/-0.28 in DOG compared to control of 2.36+/-1.13 and the phagocytic rate of albumin coated paraffin oil droplets was 0.029+/-0.01 mg PO/10(7) PMN/minute in DOG compared to control of 0.048 mg PO/10(7) cells/minute. When ATP levels were maintained by the simultaneous addition of 5 mM glucose or pyruvate to media containing DOG, latex ingestion was improved to 1.15+/-0.3 with glucose and 1.59+/-0.64 with pyruvate and albumin coated particles to 0.045+/-0.01 mg PO/10(7) PMN/minute with pyruvate. There was no improvement in the uptake of either the C3 dependent particles or IgG coated Pneumococci in media containing DOG and glucose and/or pyruvate. Following the removal of DOG from the extracellular medium and the addition of pyruvate or glucose, phagocytosis of C3 dependent LPS-PO was restored to normal values. Neither the binding of C3 or IgG coated particles to the PMN nor the lateral movement of glycoprotein utilizing concanavalin A capping was affected by DOG. Thus, the presence of DOG in the PMN containing adequate amounts of ATP will selectively and reversibly inhibit those surface events required for phagocytosis of C3 and IgG bound particles but not latex particles or albumin particles which non-specifically bind to PMN.

Effect of Concanavalin A on Membrane Potential of Polymorphonuclear Leukocyte Monitored by Fluorescent Dye

Changes in fluorescence intensity of the dye 3, 3'-dipropylthiodicarbocyanine iodide were monitored in guinea pig polymorphonuclear leukocytes (PMN) in the presence of reagents that modulate plasma membrane dynamics. Valinomycin, a specific K+ ionophore, increased fluorescence intensity as a function of log K+ concentration in incubation medium. The fluorescence was intensified by treating cells with concanavalin A, and 100μg/ml of the lectin was required for a half maximum change. The change was temperature dependent. It was inhibited by potent depressants of membrane fluidity, such as cholesterol ester and cepharanthine, or by colchicine which degrades microtubules. Cytochalasin B which degrades microfilament assembly stimulated fluorescence change. The change was also dependent on the ionic environment and energy state of PMN. These data suggest that the fluidity of the surface membrane and cytoskeletal system are closely related to changes in PMN membrane potential. The data further suggest that the changes might be involved in the concanavalin A-related transmembrane control mechanism.

The alteration of superoxide dismutase, catalase, glutathione peroxidase, and NAD(P)H cytochrome c reductase in guinea pig polymorphonuclear leukocytes and alveolar macrophages during hyperoxia.

Superoxide dismutase, catalase, glutathione peroxidase and NAD(P)H cytochrome c reductase were quantitated in polymorphonuclear leukocytes (PMN) and alveolar macrophages (AM) obtained from guinea pigs exposed up to 90 h to 85% oxygen. PMN and AM were sonicated and separated into a 16,000-g pellet, a 100,000-g pellet, and a 100,00-g supernate. Superoxide dismutase activity increased in both cells within 18 h, persisted for 66 h and decreased by 90 h. The highest rate of increase was in the 100,000-g pellet containing 3.4% of total enzyme activity in PMN but 28% in AM. The enzyme induction in PMN and AM was partially inhibited by daily intracardiac injections of 50 mg/kg actinomycin D. During oxygen exposure, catalase activity in PMN and AM decreased to 60% of its original activity, and gluthathione peroxidase was reduced in PMN to 60% and in AM to 20% of control values. Although NAD(P)H cytochrome c reductase decreased to 50% in PMN, no change was noted in AM. Upon exposure to superoxide anion, purified catalase, the glutathione peroxidase of the 100,000-g supernate, NADH, and NADPH cytochrome c reductases of the 16,000-g pellet decreased to 66+/-5%, 72+/-4%, 52+/-8%, and 40+/-9%, respectively, of their original activity. This inactivation was prevented by 0.1 mg superoxide dismutase. These in vitro observations could explain the decreased catalase and glutathione peroxidase activity demonstrated in vivo that may lead to an intracellular accumulation of hydrogen peroxide. Increased hydrogen peroxide concentrations have been found to inactivate superoxide dismutase thus impairing the first defense mechanism against superoxide anion.

A role of cathepsin B I∗ in polymorphonuclear leukocytes chemotaxis

Cathepsin B I ∗ was purified from rat liver lysosomal fraction by ammonium sulfate fractionation, followed by chromatography on Sephadex G-200 and DEAE-Sephadex. Formation of chemotactic factor for guinea pig polymorphonuclear (PMN) leukocytes was demonstrated in vitro when guinea pig serum was incubated with cathepsin B I. This factor formation was dependent on SH-reagent dithiothreitol (DTT) and was maximal at pH 6.0. ZnSO 4, an inhibitor of cathepsin B I, inhibited the chemotactic factor formation likewise.

Antigenic differences between the outer and inner surfaces of plasma membranes of polymorphonuclear leukocytes shown with immunoferritin

Antigenic differences between the exterior and interior (cytoplasmic) surfaces of the plasma membrane of guinea pig polymorphonuclear leukocytes (gp-PMNL) were examined using an improved indirect immunoferritin technique. The antibodies at the exterior surface of the cells were isolated from antiserum to gp-PMNL by adsorption onto and elution from the cell surface. Plasma membranes were prepared as large open sheets using an aqueous two-phase polymer system and the outer surfaces of the membranes were distinguished by their reactivity with influenza virus. After incubation of the plasma membrane preparation, first with antibodies to the exterior surface of the cell, and then with refined ferritin-conjugate, most (>95%) of the ferritin was found on the exterior surface of the plasma membrane with very little (<5%) on the cytoplasmic surface. In contrast after incubation with antibodies to the 100 000 g supernatant fraction of cells under the same conditions, most of the ferritin was found on the cytoplasmic side. Thus, using this antibody preparation against the cell surface, we could find scarcely any antigenicity common to both sides of the plasma membrane.

Inhibitory action of D-galactose on phagocyte metabolism and function.

To account for enhanced susceptibility to infection among galactosemics, the acute effects of D-galactose on metabolic and functional activities of phagocytic cells in vitro were investigated. Human and guinea pig polymorphonuclear leukocytes (PMN) when incubated in medium containing 30 mM galactose displayed substantially less killing of Escherichia coli than when incubated in medium with 5 mM glucose. Impaired bactericidal activity was dependent upon galactose concentration but could be partially averted by supplementing the galactose-containing medium with 15 mM glucose. Phagocytic activities of guinea pig PMN and peritoneal macrophages were assayed by following ingestion of 32P-labeled E. coli and were also depressed by elevated galactose. Galactose was readily epimerized to glucose by resting PMN, and this conversion was stimulated by phagocytosis. Incubation of macrophages in the presence of galactose resulted in depletion of intracellular levels of adenosine 5' -triphosphate as well as other metabolities.