Role of oxygen in antibody-dependent cytotoxicity mediated by monocytes and neutrophils

NADPH oxidase is required for neutrophil-dependent autoantibody-induced tissue damage

The contribution of phagocyte-derived reactive oxygen species to tissue injury in autoimmune inflammatory diseases is unclear. Here we report that granulocyte nicotinamide adenine dinucleotide phosphate (NADPH) oxidase crucially contributes to tissue injury in experimental models of the antibody-mediated autoimmune disease epidermolysis bullosa acquisita. Neutrophil cytosolic factor 1-deficient mice lacking functional NADPH oxidase were resistant to skin blistering by the passive transfer of antibodies against type VII collagen. Pharmacological inhibition or deficiency of human NADPH oxidase abolished dermal-epidermal separation caused by autoantibodies and granulocytes ex vivo. In addition, recruitment of granulocytes into the skin was required for tissue injury, as demonstrated by the resistance to experimental blistering of wild-type mice depleted of neutrophils and of CD18-deficient mice. Transfer of neutrophil cytosolic factor 1-sufficient granulocytes into neutrophil cytosolic factor 1-deficient mice demonstrated that granulocytes provide the NADPH oxidase required for tissue damage. Our findings identify granulocyte-derived NADPH oxidase as a key molecular effector engaged by pathogenic autoantibodies and provide relevant targets for prevention of tissue damage in granulocyte-mediated autoimmune diseases.

Granzyme B and perforin: constitutive expression in human polymorphonuclear neutrophils

Polymorphonuclear neutrophils (PMNs) produce an abundance of bactericidal and cytotoxic molecules consistent with their role as first-line defense against bacterial infection. PMNs, however, also cause efficient cellular cytotoxicity when targeted through Fc receptors to appropriate antibody-coated target cells. Although this so-called antibody-dependent cellular cytotoxicity (ADCC) was described many years ago, the mechanism of killing is still elusive. We now have found that PMNs contain perforin and granzyme B, the 2 molecules known as the cytotoxic entity of natural killer cells and of cytotoxic T lymphocytes as well. Lysates of PMNs were lytic for chicken erythrocytes in a time-, temperature-, and Ca2+-dependent manner. Moreover, apoptosis of Jurkat cells was induced, consistent with the observation that the PMN lysates contain enzymatically active granzyme B. Taken together, our data provide evidence for the presence of perforin and granzyme B within the cytotoxic arsenal of PMNs. (Blood. 2004;103:1099-1104)

Granulocyte colony-stimulating factor inhibits the mitochondria-dependent activation of caspase-3 in neutrophils

The exact mechanism of apoptosis in neutrophils (PMNs) and the explanation for the antiapoptotic effect of granulocyte colony-stimulating factor (G-CSF) in PMNs are unclear. Using specific fluorescent mitochondrial staining, immunofluorescent confocal microscopy, Western blotting, and flow cytometry, this study found that PMNs possess an unexpectedly large number of mitochondria, which are involved in apoptosis. Spontaneous PMN apoptosis was associated with translocation of the Bcl-2-like protein Bax to the mitochondria and subsequent caspase-3 activation, but not with changes in the expression of Bax. G-CSF delayed PMN apoptosis and prevented both associated events. These G-CSF effects were inhibited by cycloheximide. The general caspase inhibitor z-Val-Ala-DL-Asp-fluoromethylketone (zVAD-fmk) prevented caspase-3 activation and apoptosis in PMNs, but not Bax redistribution. PMN-derived cytoplasts, which lack a nucleus, granules, and mitochondria, spontaneously underwent caspase-3 activation and apoptosis (phosphatidylserine exposure), without Bax redistribution. zVAD-fmk inhibited both caspase-3 activation and phosphatidylserine exposure in cultured cytoplasts. Yet, G-CSF prevented neither caspase-3 activation nor apoptosis in cytoplasts, confirming the need for protein synthesis in the G-CSF effects. These data demonstrate that (at least) 2 routes regulate PMN apoptosis: one via Bax-to-mitochondria translocation and a second mitochondria-independent pathway, both linked to caspase-3 activation. Moreover, G-CSF exerts its antiapoptotic effect in the first, that is, mitochondria-dependent, route and has no impact on the second.

Early Membrane Rupture Events During Neutrophil-Mediated Antibody-Dependent Tumor Cell Cytolysis

Although cell-mediated cytolysis is a fundamental immune effector response, its mechanism remains poorly understood at the cellular level. In this report, we image for the first time transient ruptures, as inferred by cytoplasmic marker release, in tumor cell membranes during Ab-dependent cellular cytolysis. The cytosol of IgG-opsonized YAC tumor cells was labeled with tetramethylrhodamine diacetate followed by the formation of tumor cell-neutrophil conjugates. We hypothesized that tumor cell cytolysis proceeds via a series of discrete membrane rupture/resealing events that contribute to marker release. To test this hypothesis, we occluded the fluorescence image of the labeled tumor cells by passing an opaque disk into a field-conjugated plane between the light source and the sample. Multiple small bursts of fluorescent label release from tumor cells could be detected using a photomultiplier tube. Similarly, multiple fluorescent plumes were observed at various sites around the perimeter of a target. These findings support a multihit model of target cytolysis and suggest that cytolytic release is not focused at specific sites. Cytolytic bursts were generally observed at 20-s intervals, which match the previously described reduced nicotinamide-adenine dinucleotide phosphate and superoxide release oscillation periods for neutrophils; we speculate that metabolic oscillations of the effector cell drive the membrane damage of the target.

Defensins: a family of antimicrobial and cytotoxic peptides

Defensins are antimicrobial and cytotoxic peptides that contain 29-35 amino acid residues, including 6 invariant cysteines that form 3 intramolecular disulfide bonds. They constitute more than 5% of the total cellular protein of human and rabbit neutrophils (PMN), and are also produced by rabbit lung macrophages and by murine and human small intestinal Paneth cells. Defensins exerted antimicrobial effects in vitro against many Gram-positive and Gram-negative bacteria, fungi, mycobacteria and some enveloped viruses, and were cytotoxic to a wide range of normal and malignant targets, including cells resistant to TNF-alpha and NK-cytolytic factor. Human and rabbit defensins formed voltage-sensitive channels in a variety of planar lipid bilayers when a negative voltage of approximately 70-90 mV was applied to the contralateral side. These channels showed modest anion selectivity and their formation was strongly influenced by defensin concentration. Although most other channel-forming peptides have prominent alpha-helical domains, the structure of defensin molecules is primarily composed of antiparallel beta-sheets. Studies with various prokaryotic and eukaryotic cells provided convincing evidence that defensins killed these targets by forming voltage-regulated channels in the susceptible cell's membrane. The broad spectrum of defensin-susceptible targets and the abundance of defensins in specialized host defense cells of the blood, lungs and intestinal tract suggest that defensins could play a significant role in innate immunity to infection and neoplasia.

Deposition of reactive oxygen metabolites onto and within living tumor cells during neutrophil-mediated antibody-dependent cellular cytotoxicity

In this study we test the hypothesis that reactive oxygen metabolites are delivered from neutrophils to simultaneously both the cell surface and cytosol of opsonized YAC erythroleukemic target cells. Using 5' (or 6') carboxyl-2',7'-dichlorodihydrofluorescein (H2-CDCF) diacetate as starting material, we synthesized its succinimidyl ester derivative. H2-CDCF-conjugated IgG prepared from the succinimidyl ester derivative was used to opsonize targets. In vitro studies have shown that H2-CDCF becomes fluorescent upon exposure to reactive oxygen metabolites, including hydrogen peroxide. Using video intensified epifluorescence microscopy, we observed that reactive oxygen metabolites are deposited on tumor cell membranes during neutrophil-mediated antibody-dependent cellular cytotoxicity (ADCC). This deposition process is catalase sensitive. The role of reactive oxygen metabolites produced by neutrophils in triggering the oxidation of H2-CDCF is further supported by the observation that neutrophils from chronic granulomatous disease (CGD) patients did not affect target fluorescence. YAC tumor cells were also labeled with dihydrorhodamine 123 or dihydrotetramethylrosamine. The oxidized forms of these reagents were found within the cytoplasm of YAC cells. During ADCC normal neutrophils, but not neutrophils obtained from CGD patients, triggered the oxidation of dihydrorhodamine 123 and dihydrotetramethylrosamine within tumor cells. Using two-color automated epifluorescence microscopy, we could not detect temporal intermediates with fluorescence in only one compartment, i.e., either solely on the plasma membrane or in the cytoplasm. These observations suggest that reactive oxygen metabolites cross target membranes (< 12 sec. These studies show that reactive oxygen metabolites are deposited both onto and into tumor cells during ADCC, wherein both compartments could become vulnerable to oxidant-mediated damage.

Role of oxygen intermediates in cytotoxicity: studies in chronic granulomatous disease

The ability of human neutrophils to lyse various target cells was investigated using cells from normal individuals and from patients with chronic granulomatous disease (CGD) whose cells lack the ability to form reactive oxygen intermediates (ROI). Cytolysis was stimulated by phorbol myristate acetate (PMA), rabbit antiserum, and a heteroantibody that binds to both the FcRII receptor of neutrophils and to the target. The PMA-activated CGD neutrophils were deficient compared to controls in killing both tumor and chicken erythrocyte (CRBC) targets at all effector-target ratios in 18-h assays. When CRBC were sensitized with rabbit antiserum, the normal cells still killed slightly more. When killing of CRBC was mediated by the heteroantibody, however, cytotoxicity of CGD neutrophils exceeded that of normal cells. CGD mononuclear cells (MNC) killed tumor cell targets as well as or better than normal MNC. Thus, PMA-mediated cytolysis appears to depend primarily upon the ability of the cell to generate ROI whereas antibody-mediated cytotoxicity and MNC-mediated lysis of tumor cells do not require ROI formation.

Extracellular acidic pH modulates oxygen-dependent cytotoxic responses mediated by polymorphonuclear leucocytes and monocytes

In the present study, we compared the ability of human neutrophils and monocytes to display oxygen-dependent cytotoxic responses at pH 7.4 and 6.2. Our results show that cytotoxicity induced by immune complexes (IC), zymosan, N-formyl-methionyl-leucyl-phenylalanine (FMLP) and concanavalin A (Con A) were markedly increased when they were carried out at pH 6.2 instead of pH 7.4. Cytotoxicity induced by phorbol myristate acetate (PMA), on the contrary, was significantly decreased at pH 6.2. It is noteworthy that cytotoxic responses induced by IC, zymosan and Con A were also increased when, 2 h after effector cell stimulation at pH 6.2, cytotoxicity was measured at pH 7.4. Finally, when we examined possible mechanisms involved in the augmentation of cytotoxicity, we observed that the oxidative response of IC-stimulated neutrophils, measured as chemiluminescence emission, was not increased at pH 6.2, on the contrary, it was significantly decreased. The relevance of these results is discussed.

A simple method for the purification of human peripheral blood monocytes. A substitute for Sepracell-MN

Sepracell-MN has provided a simple, rapid means of isolating peripheral blood monocytes. However this product is no longer available. Consequentially we have developed a Percoll gradient which matches Sepracell-MN in simplicity and yield of monocytes. Using this Percoll gradient, an average of 7 x 10(6) monocytes with a purity of 83% were obtained from 30-40 ml of blood. These monocytes were at least 97% viable and responded to chemotactic stimuli in comparable numbers to those prepared using Sepracell-MN.

Two different Fc gamma receptor-dependent cytotoxic mechanisms triggered by monoclonal immunoglobulins

It is known that the receptors for the Fc portion of IgG molecules (Fc gamma R) are widely distributed in cells of the immune system. The expression of Fc gamma R enables monocytes and neutrophils to destroy antibody-coated target cells through the antibody-dependent cell-mediated cytotoxicity (ADCC) mechanism. In addition, the interaction of immune complexes or aggregated IgG with monocytes or neutrophils led to the lysis of nonsensitized target cells in a process known as nonspecific cytotoxicity (NSC). Despite that ADCC and NSC are both triggered through Fc gamma R, the cytolytic mechanism involved in each reaction is different. In this paper we analyze the ability of human monoclonal IgG1, IgG2, IgG3 and IgG4 to induce ADCC and NSC. Our results demonstrate that each IgG subclass is able to induce both, NSC and ADCC, mediated by monocytes or neutrophils, indicating that there is no correlation between IgG subclass specificity and the ability to activate both mechanisms.

Cytochrome b co-fractionates with gelatinase-containing granules in human neutrophils

Subcellular fractionation studies in resting human neutrophils indicated a bimodal distribution for cytochrome b. A major peak of cytochrome b co-sedimented with gelatinase under different experimental conditions. This localization was partially overlapped with specific granules (using lysozyme and lactoferrin as specific granule markers), but clearly resolved from azurophilic granules, plasma membrane, mitochondria, as well as from a novel alkaline phosphatase-rich intracellular organelle. A minor localization of cytochrome b was found in fractions enriched in both the plasma membrane marker 5'-nucleotidase and alkaline phosphatase. A significant portion of ubiquinone cell content co-fractionated with the gelatinase-containing granules. After phorbol myristate acetate (PMA)-cell stimulation, cytochrome b was mobilized to fractions showing respiratory burst activity and enriched in 5'-nucleotidase activity. This mobilization paralleled secretion of gelatinase and lysozyme to the extracellular medium. Furthermore, neutrophil stimulation with fluoride in the absence of cytochalasin B induced release of gelatinase and generation of superoxide anion with only minimal release of lysozyme. Preincubation of cells with the anion channel blocker 4,4'-diisothiocyanostilbene-2,2'-disulfonic acid (DIDS) prevented lysozyme release, but had only a minor effect on the release of gelatinase and did not inhibit the superoxide anion generation elicited by N-formyl-methionyl-leucyl-phenylalanine or PMA. These results suggest a main location of cytochrome b in mobilizable gelatinase-containing granules, which can constitute a subpopulation of specific granules. Furthermore, these findings show that the gelatinase-containing granule is functionally involved in the respiratory burst in neutrophils and that membrane fusion between plasma membrane and the gelatinase-containing granule occurs during activation of cells.

Effect of auranofin on eicosanoids and protein kinase C in human neutrophils

Auranofin (AF), a lipophilic chrysotherapeutic agent, was investigated for its effect on the formation of lipoxygenase products and the activity of protein kinase C in human neutrophils. We have previously shown that inhibition of LTB4 formation by 5-lipoxygenase (5-LO) inhibitors is intimately associated with a marked increased in 15-HETE in excess of arachidonic acid. The calcium- and phospholipid-dependent protein kinase, protein kinase C, is activated in FMLP- and A23187-stimulated neutrophils, is hypothesized to stimulate superoxide generation, and plays an essential role in eicosanoid production. AF dose-dependently inhibited the generation of leukotriene B4(LTB4) in FMLP-stimulated neutrophils, the ID50 was approximately 4.5 micrograms/ml. Unlike known 5-LO inhibitors, AF did not enhance the production of 15-HETE. In neutrophils stimulated with the calcium ionophore, A23187, AF did not inhibit the generation of LTB4 nor did AF change the 15-HETE levels. AF inhibited superoxide generation in FMLP-stimulated neutrophils dose-dependently, but did not change the activation of protein kinase C in the cells. We therefore conclude, that AF inhibition of LTB4 production in neutrophils is different from 5-lipoxygenase inhibitors and is elicited at a step distal to protein kinase C activation.

Antibody-coated target cell membrane-induced chemiluminescence by human polymorphonuclear leukocytes

Activation of the oxidative metabolic burst of human polymorphonuclear leukocytes (PMN) by antibody-coated crude membrane fragments of K562 tumor cells was measured in a luminometer. Induction of the chemiluminescence (Cl) response was measured in the presence of luminol and lucigenin. The Cl was dependent on the concentration of PMN, the enhancer luminol or lucigenin, and the amount of tumor cell fragments and anti-K562 serum. PMN were not triggered to a Cl response in the absence of antibodies. The lucigenin-enhanced Cl involved superoxide anion detection while the luminol-enhanced Cl was dependent on the presence of myeloperoxidase and involved hydroxyl radicals. An intact cytoskeleton and energy were necessary for an optimal Cl response.

Role of oxygen-dependent mechanisms in monoclonal-antibody-induced lysis of normal T cells by phagocytes. II. Murine phagocytes

In the first part of this study, we reported that antibody-dependent cellular cytotoxicity (ADCC) mediated by human polymorphonuclear (PMN) and mononuclear (MN) phagocytes against anti-T-cell monoclonal-antibody-(mAb)-coated T lymphocytes, is mainly dependent upon the generation of reactive oxygen intermediates (ROI) for PMN, whereas MN-mediated ADCC depends on both oxidative and non-oxidative cytolytic events. Using mouse effector cells from various organs and at various maturation or activation states, the present report shows that in this ADCC model against mAb-coated normal T cells, resident spleen (SPC) and peritoneal exudate (PEC) cells selectively bound and developed oxidative responses to these mAb-coated normal target cells but remained ineffective in ADCC. Similar data were obtained with inflammatory recruited (thioglycollate-elicited or Biogel granuloma-induced) macrophages, whereas immunologically activated macrophages (from BCG-treated mice) mediated both strong oxidative responses and potent ADCC reactions. In contrast, and as in the human system, both resident (from bone marrow) and inflammatory PMN phagocytes exerted significant lysis of these mAb-sensitized normal lymphoid cells. These findings, which are similar to those reported in ADCC against tumour target cells, strongly suggest that the nature (normal or tumoral) of the target cell does not influence the lytic mechanisms of macrophage-mediated ADCC and that these latter require activated macrophages and, like PMN, involve strong (if not exclusive) ROI participation.

Different activation pathways involved in antibody-dependent and immune-complexes-triggered cytotoxicity mediated by neutrophils

We have shown previously that normal human neutrophils triggered by immune complexes displayed significant levels of cytotoxicity towards non-sensitized target cells (non-specific cytotoxicity-NSC) (Geffner, J. R. et al. 1987). Despite the fact that NSC and antibody-dependent cellular cytotoxicity (ADCC) are both mediated through neutrophil Fc gamma R and require the activation of the respiratory burst, the cytolytic mechanisms involved in each case appear to be different. In order to analyse the pathways of activation involved in the induction of NSC and ADCC, we studied here some of the metabolic requirements associated with each cytotoxic function. Our results suggest that ADCC is dependent on Na+/H+ antiporter activity, de novo protein synthesis, availability of external Ca2+ and calmodulin activity, activation of phospholipase C and activation of protein kinase C. On the other hand, NSC appears to be dependent on availability of external Ca2+ and calmodulin activity and activation of phospholipase A2. These results indicate that different pathways of activation are involved in the induction of neutrophil-mediated ADCC and NSC.

In vitro inhibition of leukotriene B4 formation by exogeneous 5-lipoxygenase inhibitors is associated with enhanced generation of 15-hydroxy-eicosatetraenoic acid (15-HETE) by human neutrophils

Leukotrienes, products of the 5-lipoxygenase pathway of arachidonic acid metabolism, have been suggested to play a pathogenic role in psoriasis, because of their ability to induce skin inflammation and to stimulate epidermal proliferation. The 15-lipoxygenase product 15-hydroxy-eicosatetraenoic acid (15-HETE) has no proinflammatory capacity. In contrast, it can inhibit the activity of the 5-lipoxygenase. The purpose of the present study was to study the effect of 5-lipoxygenase inhibitors on the formation of 15-HETE by human neutrophils in vitro. Purified neutrophils were incubated with A 23187 (5 microM) and arachidonic acid (25 microM) with and without different inhibitors of 5-lipoxygenase activity (RS 43179, benoxaprofen, NDGA, and CP 66248). Methods for identifying eicosanoids included RP-HPLC and radioimmunoassay. Formation of leukotriene B4 was inhibited in a dose-dependent way, which was strongly correlated with a concomitant increase in the formation of 15-HETE (r = 0.97, p less than 0.01). The cyclooxygenase inhibitor indomethacin did not change 15-HETE formation. The stimulation of 15-HETE formation was not associated with cell damage as assessed by LDH release. Furthermore, identical incubations of T lymphocytes, characterized by a low 5-lipoxygenase activity, did not result in increased 15-HETE formation. These results show that inhibition of 5-lipoxygenase activity can lead to increased formation of 15-HETE. Because 15-HETE inhibits formation of 5-LO products, it may amplify the effect of 5-lipoxygenase inhibitors.

Heterogeneous distribution of lipoxygenase products in psoriatic skin lesions

Several biologically active lipoxygenase products or arachidonic acid (AA) have been demonstrated in psoriatic skin lesions. The purpose of the present study was to determine the amounts of the different lipoxygenase products simultaneously in psoriatic skin. Slices of psoriatic skin were obtained at different levels with a keratome. Extracted lipids were identified by high performance liquid chromatography, UV-absorption spectrum, radioimmunoassay, and chemokinesis. Leukotriene B4 (LTB4), and 12- and 15-hydroxy-eicosatetraenoic acid (HETE) were detected in most psoriatic lesions. However, there was a remarkable variation from lesion to lesion. The biopsy specimens contained: 276.2 +/- 126.0 pg/g wet tissue of LTB4, 3,130.0 +/- 2,898.0 ng/g wet tissue of 12-HETE, and 3,633.0 +/- 1,692.0 ng/g wet tissue of 15-HETE. No correlation was found between the levels of the different lipoxygenase products. The content of each of the identified lipoxygenase products was higher in the superficial part of the biopsy specimen consisting of approximately two-thirds of the epidermis plus papillary dermis than in the lower part consisting of approximately one-third of the epidermis plus some reticular dermis. Also, there was a great variation from one anatomical region to another within the same patient. Because these lipoxygenase products possess different biological activities, the variation in their occurrence may be important for understanding their potential role in psoriasis. To determine which lipoxygenase products may be of pathogenic importance, analysis of early psoriatic lesions is warranted.

Neutrophil-mediated cytotoxicity triggered by immune complexes: the role of reactive oxygen metabolites

Normal human neutrophils triggered by precipitating immune complexes (IC), soluble IC (sIC) or heat-aggregated IgG (HAIgG) displayed low levels of cytotoxicity towards nonsensitized target cells. Catalase, but not heated catalase, completely impaired this nonspecific cytotoxicity (NSC), suggesting a key role for hydrogen peroxide (H2O2) in the lysis of target cells. Superoxide dismutase (SOD) and certain HO. and 1O2 scavengers were unable to exert significant effects. Three haem-enzyme inhibitors, sodium azide, sodium cyanide and 3-amino-1,2,4-triazole did not decrease neutrophil NSC, but markedly enhanced it. This data suggest that the mechanism involved was not dependent upon myeloperoxidase (MPO). The analysis of neutrophil-mediated ADCC indicates that oxygen-dependent but MPO-independent mechanisms appeared to be operative in this system. It was also found that the microfilament disrupting agents, cytochalasin B (CB) and dihydrocytochalasin B (dhCB), as well as the chemotactic peptide N-formyl-methionyl-leucyl-phenylalanine (FMLP), significantly enhanced NSC. In contrast, these compounds partially inhibited ADCC. This cytotoxic system provides a suitable model to study events that may occur during the course of immune complex diseases and also permits the evaluation of alternative lytic mechanisms triggered through neutrophil Fc gamma receptors.

Inhibition by leukotriene B5 of leukotriene B4-induced activation of human keratinocytes and neutrophils

Leukotriene B5 (LTB5) that is generated enzymatically from eicosapentaenoic acid (EPA), was compared with arachidonic acid-derived LTB4 for its DNA synthetic effect on cultured human epidermal keratinocytes and for its chemokinetic effect on human blood neutrophils. Leukotriene B5 was much less potent than LTB4 in stimulating DNA synthesis and in inducing chemokinesis. Furthermore, the maximum response to LTB5 was only a mean of 38% that of LTB4 for mitogenesis and 70% that of LTB4 for chemokinesis. At an optimally active concentration of LTB4 (10(-10) M) the addition of LTB5 suppressed the enhancement by LTB4 of DNA synthesis in keratinocytes by a mean of 21%, 33%, and 54%, respectively, at 10(-9) M, 10(-8) M, and 10(-7) M LTB5. Leukotriene B5 inhibited to a lesser extent the maximum neutrophil chemokinetic response elicited by 10(-10) M LTB4 with mean inhibition of 10%, 20%, and 18%, respectively, by 10(-9) M, 10(-8) M, 10(-7) M LTB5; LTB5 was without effects on N-formyl-L-methionyl-L-leucyl-L-phenylalanine (FMLP)-elicited neutrophil chemokinesis and on thrombin-stimulated keratinocyte DNA synthesis. The dietary introduction of n-3 fatty acids, such as EPA, may reduce the epidermopoiesis and neutrophil migration evoked by LTB4 through decreases in generation of LTB4 and the capacity of LTB5 to inhibit the effects of LTB4.

Human monocyte and polymorphonuclear leukocyte chemotactic and chemokinetic responses to leukotriene B4 and FMLP

Comparable investigations of the chemotactic and chemokinetic responses of purified monocytes (MO) and polymorphonuclear leukocytes (PMN) to leukotriene B4 (LTB4) and N-formyl-methionyl-leucyl-phenylalanine (FMLP) were made in this study. Using a sensitive and objective 51Cr-chemotactic assay, it was shown that both MO and PMN showed a bell-shaped response to LTB4 and FMLP, with a maximum response at 10(-8)M for both drugs. For PMN, the maximal response elicited by LTB4 was similar in magnitude to that produced by FMLP, whereas the MO chemotaxis induced by 10(-8)M FMLP was significantly higher than the response evoked by 10(-8)M LTB4. For both cell types, LTB4 at low concentrations (less than 10(-9)M) gave rise to higher chemotactic responses than FMLP. Chemokinesis was differentiated from chemotaxis, using a checkerboard system. At concentrations less than 10(-9)M the LTB4-evoked contribution of chemokinesis to the total migrational response was significantly higher than the chemokinetic contribution of FMLP. Preincubation with LTB4 produced only homologous chemotactic deactivation to subsequent LTB4 stimulation, whereas preincubation with FMLP resulted in diminished secondary response to both FMLP and LTB4. The degree of deactivation was dependent upon the dose of attractant used, with a LTB4 concentration of 10(-7)M leading to about 40% and 25% deactivation of PMN and MO, respectively. Preincubation with 10(-7)M FMLP led to about 50% and 32% suppression of the subsequent chemotactic response of PMN and MO, respectively.

Modulation of porcine peripheral blood-derived macrophage functions by in vitro infection with African swine fever virus (ASFV) isolates of different virulence

Macrophages play an important role in defense against invading pathogens and neoplastic diseases. Their ability to maintain their functional characteristics is also important in the survival of the host. Loss of macrophage function during infection may be important in determining resistance or susceptibility of a host species. In this communication, we describe the effect of ASFV replication, in macrophages in vitro, on the functional characteristics of these cells. Infection with ASFV did not alter the expression of Fc receptors nor their ability to mediate ADCC. However, African swine fever virus was shown to modulate antibody mediated phagocytosis, chemiluminescence and chemotaxis. Similar modulation of certain macrophage functions was observed with ASFV isolates that differed in their virulence. We were therefore, unable to correlate the virulence of ASFV with the ability to alter macrophage function.

Monocyte and neutrophil chemotaxis in psoriasis. Relation to the clinical status and the type of psoriasis

Chemotactic activity of purified monocytes and polymorphonuclear leukocytes was studied in fifty patients with psoriasis vulgaris and in forty-five healthy individuals by an objective in vitro assay with the use of a 51Cr-labeling technic. Both monocytes and polymorphonuclear leukocytes showed a statistically significant increase in chemotactic response, which was positively correlated with disease activity but not with the extent of the cutaneous lesions. The chemotactic activity of monocytes correlated with that of polymorphonuclear leukocytes in the same patients. Exacerbation of psoriasis was preceded by a rapid increase of polymorphonuclear leukocyte chemotaxis, and a decline of chemotaxis occurred during clinical improvement. The psoriatic leukocytes were 22% more sensitive than normal leukocytes to leukotriene B4 than to N-formyl-methionyl-leucyl-phenylalanine. Psoriatic plasma showed chemotaxis-enhancing properties, but only in patients with widespread cutaneous lesions. Additionally, monocyte and polymorphonuclear leukocyte chemotaxis was studied in twenty patients with pustular psoriasis and in fifteen patients with psoriatic arthritis. The chemotactic profiles in pustular psoriasis were different from those in psoriasis vulgaris. Patients with pustular psoriasis had significantly higher polymorphonuclear leukocyte chemotaxis than patients with psoriasis vulgaris, but the chemotactic activity of monocytes was normal. The presence of seronegative arthritis had no influence on chemotactic activity of psoriatic leukocytes.

Epidermis and lymphocyte interactions during a tuberculin skin reaction. II. Epidermis contains specific lymphocyte chemotactic factors

Lymphocyte chemotaxis was studied in a blind-well chamber assay by measuring the passage of 51Cr-labeled cells through a polycarbonate filter with a pore size of 5 micron. Monocyte-depleted lymphocytes were divided into T cells (E receptor-positive lymphocytes) and non-T cells. T lymphocytes showed pronounced migration after exposure to leukotriene B4 (LTB4) and casein, and weak migration after exposure to N-formyl-methionyl-leucyl-phenylalanine (FMLP). Non-T cells showed strong migration after exposure to FMLP, but weak migration after exposure to casein and LTB4. Supernatants of homogenized suction blisters from normal skin did not induce active migration. However, if the epidermis came from an area overlying a positive tuberculin skin reaction, there was a significant migration mostly of T, but also of non-T cells. Supernatants from phytohemagglutinin (PHA)-stimulated lymphocyte cultures also contained lymphocyte chemotactic factor(s), which, however, had an effect only on T lymphocytes. Purified protein derivative of tuberculin (PPD)-stimulated lymphocytes did not produce chemoattractants either for T or for non-T cells. These studies show that lymphocytes can show active, directed migration following exposure to well-known chemotaxins for granulocytes and monocytes although their migrational capability differs for different subpopulations. Epidermis overlying a cell-mediated immune reaction (tuberculin) contains epidermal lymphocyte chemotactic factor(s). This factor(s) may be of importance for the type of cell infiltrate occurring in certain dermatologic disorders.

Discoid lupus erythematosus-like skin lesions in a patient with autosomal recessive chronic granulomatous disease

A case of chronic granulomatous disease (CGD) in a 32-year-old female with two episodes of opportunistic infections is described. At the age of 29 the patient was suspected to be a carrier of X-linked CGD on the basis of discoid lupus erythematosus-like skin lesions. No respiratory burst activity, as measured by phorbol myristate acetate stimulated superoxide production, was observed in isolated neutrophils of the patient. Membrane-rich fractions elicited no superoxide production in the presence of NADPH. The neutrophil content of cytochrome b-245 was within normal range. Family investigations revealed neither cellular abnormalities nor any history of skin diseases or opportunistic infections in first degree relatives. The parents of the patient were first cousins. On the basis of family history and the in-vitro assessment of neutrophil function, the patient is believed to have autosomal recessive CGD. The presented case illustrates that lupus erythematosus-like skin lesions are not restricted to female carriers of X-linked CGD, but may also be found in the autosomal recessive type of the disease.

In vitro synthesis of 12-hydroxy-eicosatetraenoic acid is increased in uninvolved psoriatic epidermis

Certain arachidonic acid (AA) metabolites have been detected in psoriatic skin lesions. In this study the capacity of normal epidermis and clinically uninvolved psoriatic epidermis to transform AA into lipoxygenase products was determined in vitro. After incubating homogenized epidermis with exogenous AA, the extracted lipids were isolated by reverse-phase high-performance liquid chromatography. Each chromatographic peak was characterized by its UV absorption spectrum and identified by its coelution with the appropriate authentic standard and by radioimmunoassay of its eluate fraction. Identified compounds were quantitated by integrated UV absorbance. Leukotriene B4 (LTB4) was also identified by neutrophil chemokinesis. Normal epidermis generated 15-hydroxy-eicosatetraenoic acid (15-HETE) and 12-HETE, the latter being more abundant. 5-Lipoxygenase products (LTB4, LTC4, and 5-HETE) were not detected. However, an unknown compound exhibiting a triplet UV absorbtion spectrum with maximum at 274 mm was formed. Its formation was inhibited by 5,8,11,14-eicosatetraynoic acid, but not by indomethacin or a specific 5-lipoxygenase inhibitor (REV 5901). These data suggest that a di-HETE with a triene structure is one possible candidate for the unknown compound. Compared with normal epidermis, the formation of 12-HETE and the unknown di-HETE by uninvolved psoriatic epidermis was increased by 54% and 63%, respectively. The formation of 12-HETE and the unknown di-HETE in uninvolved psoriatic epidermis was stimulated to the same degree in the presence of the phospholipase inhibitor quinacrine. These results indicate that uninvolved psoriatic epidermis has an increased capacity to metabolize free AA into 12-lipoxygenase products.

Superoxide production of polymorphonuclear leukocytes in surgical patients with gastric cancer

Superoxide production (SOP) by polymorphonuclear leukocytes (PMNs) in 65 gastric cancer patients, who were in preoperative state and had received no medical therapy, was assayed in order to evaluate the bactericidal activity of PMNs in cancer patients, as well as to determine the correlation of SOP by PMNs with postoperative prognoses and several factors by which extent of disease and the clinical or histological character of gastric carcinoma were defined. Patients with stage II disease had a tendency to have an increased SOP by PMNs, and furthermore, as the disease progressed, the SOP by PMNs decreased with significant depression being noted in stage III and IV cases compared to healthy controls. Significantly reduced SOP by PMNs was observed in n2 and n3 cases and with se, si, sei and/or ps(+) pathological invasion. SOP by PMNs in patients with Borrmann II type and/or poorly differentiated adenocarcinoma was significantly depressed. Patients who suffered from septic complications showed a significant depression in SOP by PMNs compared with the controls and no complication group. These results suggest that advanced gastric cancer patients may have defective oxidative PMN metabolism, and that a decrease of SOP is a contributory cause of high susceptibility to postoperative infection in cancer patients.

Neutrophil and monocyte chemotaxis in pustulosis palmo-plantaris and pustular psoriasis

Polymorphonuclear leukocyte (PMN) and monocyte (MN) chemotaxis in nine patients with pustulosis palmo-plantaris (PPP) and ten patients with pustular psoriasis (PP) was determined by an objective in vitro assay employing a 51Cr-labelling technique. PMN chemotaxis was significantly enhanced in both groups of patients compared with controls. MN chemotaxis was normal. There was no difference in the chemotactic responsiveness of leukocytes from patients with PPP and PP. The random migration of PMN and MN from the patients was normal. Homogenized tissue specimens from lesional skin with and without pustules, and from perilesional, normal-looking skin of PPP and PP were analysed for the presence of chemoattractant(s) for PMN. Lesional skin had considerable chemoattractant properties, but perilesional skin did not induce directed migration of PMNs.

Leukotrienes B4, C4 and D4 stimulate DNA synthesis in cultured human epidermal keratinocytes

Leukotrienes in psoriatic skin lesions are potent mediators of inflammation. We have studied the capacity of leukotrienes to stimulate the DNA synthesis of cultured human epidermal keratinocytes. At concentrations ranging from 10(-12) to 10(-8) M, LTB4 produced a 100% increase of DNA synthesis determined both as the incorporation of [3H] thymidine and as the labelling index. In comparison, LTB4 had no effect on the DNA synthesis of dermal fibroblast cultures. 5S,12S-LTB4 and 5S,12S-all-trans-LTB4 did not change the DNA synthesis of keratinocytes, but the effect of LTB4 was abolished in the presence of 5S,12S-all-trans HLTB4. Being less potent than LTB4 the peptidoleukotrienes (LTC4, LTD4) also stimulated keratinocyte DNA synthesis. The effect of the peptidoleukotrienes, but not of LTB4, was antagonized by FPL 55712. These results show that leukotrienes B4, C4 and D4 exert potent and stereospecific mitogenic effects on cultured human keratinocytes. The presence of these arachidonic acid metabolites in psoriatic skin lesions may be pertinent to both inflammation and aberrant epidermal growth in psoriasis.

Role of oxygen-dependent mechanisms in monoclonal antibody-induced lysis of normal T cells by phagocytes. I.--Human Phagocytes

The present study investigates the lytic potential of the reactive oxygen species (ROS) which, as previously shown in our laboratory, are generated within the first minutes following the Fc-receptor-mediated interaction between phagocytic cells and anti-T-cell monoclonal-antibody (mAb)-coated T lymphocytes. A comparative study of ROS production (measured by chemiluminescence (CL] and the cytotoxic effect (evaluated in a 51Cr release antibody-dependent cellular cytotoxicity (ADCC) assay) of human polymorphonuclear (PMN) and mononuclear (MN) cells against mAb-coated autologous, allogeneic and xenogeneic (murine) thymocytes showed that the two reactions were closely interdependent for PMN and co-existed without significant correlation for MN cells. Catalase and superoxide dismutase did not modify ADCC results, suggesting that these ROS scavengers could not diffuse into the target cell destruction area. Colchicine treatment of PMN and MN cells at a dose inhibiting phagocytosis consistently impaired their CL generation and, in parallel, strongly reduced PMN-mediated ADCC but only weakly reduced that of MN cells. PMN and MN cells from 14 patients with chronic granulomatous disease (CGD) were not capable of producing CL after contact with mAb-coated T cells and showed significantly reduced ADCC activities, while PMN and MN cells from mothers carrying the X-linked type of CGD exhibited ADCC and oxidative responses of an intermediate level. We conclude that ADCC mediated by human PMN cells against T cells is mainly dependent upon the generation of ROS, whereas that induced by MN cells is most likely effected by both oxidative and non-oxidative events.

Antibody-dependent cellular cytotoxicity and skin disease

Antibody dependent cellular cytotoxicity (ADCC) is a recently described mechanism of immunologic lysis in which cellular targets sensitized by specific antibodies are efficiently and selectively lysed by Fc receptor (FcR) bearing nonspecific effectors. Immunoglobulins of various classes (IgG, IgM, IgA, IgE) and various cellular effectors (large granular lymphocytes, monocyte/macrophages, T lymphocytes, neutrophils, and eosinophils) can induce ADCC in vitro, and the importance of ADCC in vivo is being tested experimentally in resistance to viral, bacterial, and parasitic infection, in tumor surveillance, in allograft rejection, and in inflammatory diseases. There is much indirect evidence that ADCC may be the mechanism of damage of different cellular targets in skin diseases, but the best direct evidence concerns immunologic keratinocyte damage, especially in cutaneous lupus erythematosus (LE). We have shown that keratinocytes of several species are highly susceptible to lymphocyte and monocyte-mediated ADCC, but not to neutrophil or eosinophil ADCC in vitro using two different cytotoxicity assays. In contrast, complement was a relatively ineffective mediator of lysis of metabolically intact keratinocyte targets. Patients with certain cutaneous lupus syndromes have serum antibodies capable of inducing monocyte and lymphocyte ADCC of targets coated with extractable nuclear antigens. We have shown that these antigens apparently move to the cell membrane of keratinocytes in vitro following ultraviolet irradiation. In an animal model, we have shown that antibodies to SSA/Ro bind to human keratinocytes in vivo, especially after ultraviolet irradiation. This antigen/antibody system is highly associated with 3 different photosensitive LE syndromes. The experimental linkage of UV radiation to autoantibody binding to keratinocytes and the demonstration of mononuclear cell-mediated ADCC causing keratinocyte lysis support our hypothesis that the keratinocyte damage and mononuclear cell infiltrate seen histologically in cutaneous LE are part of an ADCC process.

Effect of diethyldithiocarbamate (DDC) on human monocyte function and metabolism

Recent evidence indicates that phagocytic cells play a major role in tissue inflammation. The release of enzymes, lipid metabolites such as prostaglandins, and reactive oxygen species by these cells appear to mediate the inflammatory process. In this study we have evaluated the effects of diethyldithiocarbamate (DDC) on human monocyte function and metabolism. We demonstrate that DDC impairs that antibody-dependent cytoxicity (ADCC) of monocytes to red cell targets. The concentration of DDC which caused maximal suppression of ADCC also prevented the burst of oxidative metabolism in monocytes stimulated by sensitized red cells targets or phorbol myristate acetate (PMA). DDC also impairs the lipid metabolism of these cells as indicated by a decrement in malonyldialdehyde (MDA) production. These data indicate that DDC impairs the activity of two major biochemical pathways in monocytes which are related to the inflammatory process, i.e., the release of oxygen metabolites and prostaglandins.

Anti-tumor effect of inflammatory neutrophils: characteristics of in vivo generation and in vitro tumor cell lysis

Inflammatory neutrophils elicited by intraperitoneal injection of Corynebacterium parvum, thioglycollate or proteose peptone were capable of lysing different murine and human tumor targets in a short-term chromium-release assay. A single-cell cytotoxicity assay, which evaluated effector-target cell interactions at the single-cell level, confirmed a PMN-mediated tumor-lytic effect. Optimal lysis was achieved by PMNs obtained 6 hr after injection of C. parvum and 16 hr after injection of thioglycollate. In vitro, loss of tumor cell membrane integrity occurred extremely rapidly following conjugation with inflammatory PMNs (beginning within 15 min of the binding step). By 45 min, the lytic event was completed. Addition of catalase or superoxide dismutase to the cytotoxicity assays prevented tumor lysis in a concentration-dependent fashion, indicating that hydrogen peroxide and superoxide, products of the PMN respiratory burst, are mediators of the lytic reaction.

Autoimmune hemolysis: a critical review

Autoimmune hemolysis is defined as a shortening of erythrocyte lifespan due to antibodies directed against the individuals own red cells. This autoantibody production (by B lymphocytes) is thought to result from deficient activity of suppressor T lymphocytes. The rate of erythrocyte destruction depends on the properties of the autoantibodies and on the activities of the complement and mononuclear phagocyte systems: anemia results when destruction outweighs marrow production. Autoimmune hemolysis, which may be primary or secondary, is classified into "warm," "cold," and "mixed" types. The hemolysis associated with pregnancy. Donath-Landsteiner antibodies, of mixed type, and in children, is treated in detail. Current treatment is with immunosuppressive drugs, surgery, and plasma exchange, though immunomanipulation may become important in the future; blood transfusion may be a life-saving adjunct to other therapy.

Phorbol myristate acetate-induced modulation of antibody-dependent cellular cytotoxicity by human polymorphonuclear leukocytes

The effect of phorbol myristate acetate (PMA) on the antibody-dependent cellular cytotoxicity (ADCC) of human polymorphonuclear leukocytes (PMNs) against human erythroleukemic K562 cells was studied by the use of a 3-h 51Cr-release assay. Pretreatment of PMNs with PMA (10 ng/ml) for 60 min resulted in inhibition of subsequent ADCC. This inhibition was dependent on doses of PMA. The effect of pretreatment of PMNs with PMA on O2- generation of the cells was also studied. The ability of the cells to generate O2- was not suppressed, and the expression of Fc receptors on the cell membrane was well preserved. In contrast, the addition of PMA to the ongoing ADCC (5 to 30 min after the start of the ADCC assay) enhanced the activity of the cells for ADCC. This augmentation was abolished by catalase, whereas ADCC itself was not affected by the agent. These results imply divalent effects of PMA on the ADCC of PMNs. The suppression of ADCC activity of PMNs by pretreatment with PMA is not due to inhibition of the reactive oxygen burst of the cells. The augmentation of ongoing ADCC by the addition of PMA is due to secretion of hydrogen peroxide from the cells induced by PMA, and this augmentation occurs only when the interaction between effector and target cells exists through Fc receptor.

Studies of peripheral blood monocytes in pulmonary sarcoidosis

In 14 patients with pulmonary sarcoidosis and 14 matched controls we studied peripheral blood lymphocyte and monocyte counts, distribution of T and B lymphocytes, the functional helper:suppressor T cell balance, the antibody-dependent cell-mediated cytotoxicity of monocytes (monocyte ADCC), and the capacity of peripheral monocytes to generate angiotensin converting enzyme (ACE) in culture. Apart from lymphopenia in sarcoidosis patients we found a normal lymphocyte subset distribution and no evidence of increased suppressor T cell activity, using a PWM driven proliferative assay. The patients exhibited a normal monocyte count, but the proportion of monocytes was increased in sarcoidosis. Patients with active sarcoidosis had a significantly increased monocyte ADCC which was positively correlated with raised serum ACE. Peripheral monocytes had a measurable, but low ACE activity, which was modestly higher in active sarcoidosis than in controls. We could not reproduce earlier reported results on a glucocorticoid induced ACE synthesis from cultured human monocytes.

Antibody-dependent cellular cytotoxicity and chemiluminescence as a tool for studying the mechanism of anti-glomerular basement membrane nephritis. The role of the cytotoxic potential of polymorphonuclear granulocytes and monocytes

An in vitro system was elaborated to study the mechanisms inducing tissue injury in anti-glomerular basement membrane (GBM) nephritis. Collagenase-digested GBM (CGBM) was covalently attached to Fab' specific for chicken red blood cells (CRBC). The preparation of the CGBM-Fab' conjugate was effected by using iodoacetyl chloride coupling in analogy to a procedure described by Chiang & Koshland (1979). This conjugate was used for coating CRBC (CGBM-CRBC). In this system the antibody-dependent cellular cytotoxicity (ADCC) and the chemiluminescence mediated by purified bovine polymorphonuclear (PMN) and mononuclear cells (MNC) as well as rabbit MNC against CGBM-CRBC were compared in the presence of sheep anti-GBM IgG. All three cell populations were potent effectors in ADCC and chemiluminescence and evidence was obtained that the cytotoxic potential of MNC has to be attributed to monocytes. If compared at low effector target cell ratios in a 2 hr assay bovine PMN, however, were significantly more efficient than bovine MNC. The extent of both ADCC and chemiluminescence was directly related to the amount of anti-GBM IgG present in the system. Based on the inhibition experiments with oxygen intermediate scavengers, both ADCC and chemiluminescence by bovine PMN is dependent on generation of reactive oxygen species indicating that such radicals could play a role in vascular (endothelial) injury as documented in the loss of structural integrity of GBM.

Proton secretion by stimulated neutrophils. Significance of hexose monophosphate shunt activity as source of electrons and protons for the respiratory burst

Phagocytosis by neutrophils is accompanied by a burst in O2 consumption and activation of the hexose monophosphate shunt (HMPS). Proton secretion equal to the amount of O2 consumed is an additional feature of the respiratory burst, but its source has not been identified, nor has the source of all electrons donated to O2 in the respiratory burst. We chemically quantitated total CO2 generation in human neutrophils and found that proton secretion elicited by phagocytosis was accompanied by a stoichiometric increase in CO2 generation. Addition of carbonic anhydrase and its inhibitors had no effect on either the quantities of CO2 measured or the quantities of protons secreted. Therefore, the CO2 generated in the respiratory burst of stimulated neutrophils is hydrated to form H2CO3, which then dissociates, accounting for the observed proton secretion. Furthermore, the CO2 generated corresponds to the O2 consumed with a respiratory quotient of nearly 1. We conclude on the basis of this and previous studies that the HMPS activity is the source of both the electrons for the NADPH oxidase and of protons secreted in association with the respiratory burst.

Human polymorphonuclear leukocyte-mediated cytotoxicity against varicella-zoster virus-infected fibroblasts

Polymorphonuclear leukocytes (PMN) were studied for their ability to mediate cytotoxicity against varicella-zoster virus (VZV)-infected and uninfected human fibroblasts in 51Cr release assays. PMN were capable of mediating antibody-dependent cellular cytotoxicity (ADCC) against VZV-infected targets. Maximal ADCC was obtained with effector-to-target ratios of 100:1 and 18 h of incubation. Percent 51Cr release for 26 normal adults was 14.1 +/- 0.6 (mean +/- standard error) in the presence of pooled human seropositive sera (final dilution, 1:100) and 0.5 +/- 0.6 in the presence of pooled human seronegative sera. Addition of phorbol myristate acetate (PMA) enhanced PMN-mediated cytotoxicity against VZV-infected and uninfected targets. PMA-stimulated cytotoxicity was optimal with PMA concentrations of 200 ng/ml and effector-to-target ratios of 10:1, and antibody was not required; killing was detected as early as 3 h after incubation and was maximal after 18 h. Highly purified PMN were capable of mediating both ADCC and PMA-stimulated lysis. Catalase completely inhibited PMA-stimulated PMN cytotoxicity, but had no effect on PMN-mediated ADCC. PMN from patients with chronic granulomatous disease were capable of mediating ADCC, but not PMA-stimulated killing, against VZV-infected targets. Thus, PMN could kill VZV-infected targets by two different mechanisms: ADCC, which required antibody but not hydrogen peroxide (H2O2), and PMA-stimulated cytotoxicity, which required H2O2 but not antibody.

Control of cellular influx in lung and its role in pulmonary toxicology

The pulmonary influx of cytotoxic inflammatory cells, normally, in response to external toxins, is now thought to be etiologic in many of the disease syndromes of man, such as bronchitis and emphysema. Many types of effector inflammatory cells are involved, e.g., eosinophils, neutrophils, T-lymphocytes, monocytes. The diseases are characterized either by tissue destruction or by tissue hyperplasia. Agents which initiate the influx and cytotoxic secretions by these cells are legion and in general are not cell-specific. They include agents, such as phorbol esters, formyl peptides-complement fragments, elastin fragments, fatty acids (leukotrienes) as well as many uncharacterized excretions of inflammatory cells themselves, which react with specific receptors on the inflammatory cells, and secreted proteins such as fibronectin. Other agents, such as linoleic acid, digitonin and hydroxy fatty acids which are not bound by specific receptors also activate motility of inflammatory cells. The precise role of the above multiple cytotoxins in specific cellular fluxes in most pulmonary disease remains undefined. Similarly, the mechanism of cytotoxicity used by specific invading cells in specific pulmonary syndromes remains unclear. In general, macrophages are thought to destroy using specific proteases, neutrophils use oxidant radicals and proteases and eosinophils use basic surface active peptides. T-cells kill by unknown mechanisms. However, in specific clinical syndromes, it is usually not clear which cell is the cytotoxic culprit, nor is the mechanism of destruction usually known.

Effect of oxygen radical scavengers on K-cell cytolysis

We have shown that the hydroxyl radical scavengers sodium benzoate, phenol, dimethyl sulfoxide, sodium formate, and mannitol protect chicken erythrocyte (Ec) target cells from lysis by K-cells in plaque assays. The protection afforded by benzoate, phenol, mannitol, and dimethyl sulfoxide was abrogated if the target cells were pretreated with sodium chromate. Neither superoxide dismutase nor catalase protected Ec target cells, indicating that superoxide and H2O2 are not involved in lysis. The lysis obtained on chromium-treated Ec target cells in the presence of benzoate, phenol, and mannitol is likely due to singlet oxygen, because 1,4-diazabicyclo[2.2.2]octane and bilirubin, singlet oxygen scavengers, protected chromium-treated Ec target cells in the presence of phenol. Ec target cells not treated with chromium were not protected by either of the singlet oxygen scavengers.

Monocyte superoxide anion production in rheumatoid arthritis: preliminary evidence for enhanced rates of superoxide anion production by monocytes from patients receiving penicillamine, sodium aurothiomalate and corticosteroids

In-vitro studies of superoxide (O-2) anion production by blood monocytes after stimulation with either serum treated zymosan (STZ), IgG treated zymosan (IgGTZ), or fluoride ion (F-) were performed on cells from normal controls (n = 22) and patients with classical or definite rheumatoid arthritis (RA) (n = 35). Twenty-two of the patients were on nonsteroidal anti-inflammatory drugs (NSAID) alone and 13 were on either sodium aurothiomalate, penicillamine, corticosteroids, or a combination. Monocytes from RA patients on 'second-line therapy' showed significantly increased rates of O-2 release in response to STZ compared with normal controls, but no increase was seen in monocytes from patients on NSAID alone. With IgGTZ as the stimulus, rates of O-2 release were increased in monocytes from patients on NSAID alone compared with normal controls (p less than 0.02), but were increased to a greater extent in monocytes from patients on second-line therapy (p less than 0.01). There were no differences in basal unstimulated O-2 production and no differences after stimulation with F-. The enhanced release of O-2 by monocytes from patients on second-line therapy could not be attributed to increased disease activity and may be an effect of therapy.

Serum factors from patients with systemic lupus erythematosus enhancing superoxide generation by normal neutrophils

It has been suggested that human neutrophils exposed to performed immune complexes or activated complement fragments generate O2- anions in extracellular medium. In vivo studies have revealed that oxygen intermediates produced by immune complex-activated neutrophils play an important role in subsequent tissue damage. Since it is difficult to obtain direct evidence that O2- is released into plasma in patients with systemic lupus erythematosus (SLE), we studied the capacities of their sera to stimulate O2- release by human neutrophils in vitro. Sera from patients with SLE significantly enhanced O2- generation by neutrophils compared to normal sera. The enhancing activity of serum in the induction of increased O2- generation correlated positively with the presence of serum immune complexes and negatively with serum complement levels. The enhancing factors were analyzed by serum fractionation on Sephadex G-200 gel filtration, and were concluded to be immune complexes of intermediate size containing an activated complement fragment.

Subcellular localization of the b-cytochrome component of the human neutrophil microbicidal oxidase: translocation during activation

We describe a new method for subcellular fractionation of human neutrophils. Neutrophils were disrupted by nitrogen cavitation and the nuclei removed by centrifugation. The postnuclear supernatant was applied on top of a discontinuous Percoll density gradient. Centrifugation for 15 min at 48,000 g resulted in complete separation of plasma membranes, azurophil granules, and specific granules. As determined by ultrastructure and the distribution of biochemical markers of these organelles, approximately 90% of the b-cytochrome in unstimulated cells was recovered from the band containing the specific granules and was shown to be in or tightly associated with the membrane. During stimulation of intact neutrophils with phorbol myristate acetate or the ionophore A23187, we observed translocation of 40-75% of the b-cytochrome to the plasma membrane. The extent of this translocation closely paralleled release of the specific granule marker, vitamin B12-binding protein. These data indicate that the b-cytochrome is in the membrane of the specific granules of unstimulated neutrophils and that stimulus-induced fusion of these granules with the plasma membrane results in a translocation of the cytochrome. Our observations provide a basis for the assembly of the microbicidal oxidase of the human neutrophil.