Functional and metabolic properties of polymorphonuclear leucocytes. II. The influence of a lipopolysaccharide endotoxin

Detection of nitric oxide-mediated metabolic effects using real-time extracellular flux analysis

Dendritic cell (DC) activation is marked by key events including: (I) rapid induction and shifting of metabolism favoring glycolysis for generation of biosynthetic metabolic intermediates and (II) large scale changes in gene expression including the upregulation of the antimicrobial enzyme inducible nitric oxide synthase (iNOS) which produces the toxic gas nitric oxide (NO). Historically, acute metabolic reprogramming and NO-mediated effects on cellular metabolism have been studied at specific timepoints during the DC activation process, namely at times before and after NO production. However, no formal method of real time detection of NO-mediated effects on DC metabolism have been fully described. Here, using Real-Time Extracellular Flux Analysis, we experimentally establish the phenomenon of an NO-dependent mitochondrial respiration threshold, which shows how titration of an activating stimulus is inextricably linked to suppression of mitochondrial respiration in an NO-dependent manner. As part of this work, we explore the efficacy of two different iNOS inhibitors in blocking the iNOS reaction kinetically in real time and explore/discuss parameters and considerations for application using Real Time Extracellular Flux Analysis technology. In addition, we show, the temporal relationship between acute metabolic reprogramming and NO-mediated sustained metabolic reprogramming kinetically in single real-time assay. These findings provide a method for detection of NO-mediated metabolic effects in DCs and offer novel insight into the timing of the DC activation process with its associated key metabolic events, revealing a better understanding of the nuances of immune cell biology.

Rapid glycolytic activation accompanying innate immune responses: mechanisms and function

Innate immune responses to pathogens, mediated by activation of pattern recognition receptors and downstream signal transduction cascades, trigger rapid transcriptional and epigenetic changes to support increased expression of pro-inflammatory cytokines and other effector molecules. Innate immune cells also rapidly rewire their metabolism. The most prominent metabolic alteration following innate immune activation is rapid up-regulation of glycolysis. In this mini-review, we summarize recent advances regarding the mechanisms of rapid glycolytic activation in innate immune cells, highlighting the relevant signaling components. We also discuss the impact of glycolytic activation on inflammatory responses, including the recently elucidated links of metabolism and epigenetics. Finally, we highlight unresolved mechanistic details of glycolytic activation and possible avenues of future research in this area.

Neutrophil trafficking to the site of infection requires Cpt1a-dependent fatty acid β-oxidation

Cellular metabolism influences immune cell function, with mitochondrial fatty acid β-oxidation and oxidative phosphorylation required for multiple immune cell phenotypes. Carnitine palmitoyltransferase 1a (Cpt1a) is considered the rate-limiting enzyme for mitochondrial metabolism of long-chain fatty acids, and Cpt1a deficiency is associated with infant mortality and infection risk. This study was undertaken to test the hypothesis that impairment in Cpt1a-dependent fatty acid oxidation results in increased susceptibility to infection. Screening the Cpt1a gene for common variants predicted to affect protein function revealed allele rs2229738_T, which was associated with pneumonia risk in a targeted human phenome association study. Pharmacologic inhibition of Cpt1a increases mortality and impairs control of the infection in a murine model of bacterial pneumonia. Susceptibility to pneumonia is associated with blunted neutrophilic responses in mice and humans that result from impaired neutrophil trafficking to the site of infection. Chemotaxis responsible for neutrophil trafficking requires Cpt1a-dependent mitochondrial fatty acid oxidation for amplification of chemoattractant signals. These findings identify Cpt1a as a potential host determinant of infection susceptibility and demonstrate a requirement for mitochondrial fatty acid oxidation in neutrophil biology.

Metabolic Consequences of Efferocytosis and its Impact on Atherosclerosis

Billions of cells undergo apoptosis daily and are swiftly removed by macrophages through an evolutionarily conserved program termed "efferocytosis". Consequently, macromolecules within an apoptotic cell significantly burden a phagocyte with nutrients, such as lipids, oligonucleotides, and amino acids. In response to this nutrient overload, metabolic reprogramming must occur for the process of efferocytosis to remain non-phlogistic and to execute successive rounds of efferocytosis. The inability to undergo metabolic reprogramming after efferocytosis drives inflammation and impairs its resolution, often promoting many chronic inflammatory diseases. This is particularly evident for atherosclerosis, as metabolic reprogramming alters macrophage function in every stage of atherosclerosis, from the early formation of benign lesions to the progression of clinically relevant atheromas and during atherosclerosis regression upon aggressive lipid-lowering. This Review focuses on the metabolic pathways utilized upon apoptotic cell ingestion, the consequences of these metabolic pathways in macrophage function thereafter, and the role of metabolic reprogramming during atherosclerosis. Due to the growing interest in this new field, I introduce a new term, "efferotabolism", as a means to define the process by which macrophages break down, metabolize, and respond to AC-derived macromolecules. Understanding these aspects of efferotabolism will shed light on novel strategies to combat atherosclerosis and compromised inflammation resolution.

Intracellular and Intercellular Aspects of Macrophage Immunometabolism in Atherosclerosis

Macrophage immunometabolism, the changes in intracellular metabolic pathways that alter the function of these highly plastic cells, has been the subject of intense interest in the past few years, in part because macrophage immunometabolism plays important roles in atherosclerosis and other inflammatory diseases. In this review article, part of the Compendium on Atherosclerosis, we introduce the concepts of (1) intracellular immunometabolism-the canonical pathways of intrinsic cell activation leading to changes in intracellular metabolism, which in turn alter cellular function; and (2) intercellular immunometabolism-conditions in which intermediates of cellular metabolism are transferred from one cell to another, thereby altering the function of the recipient cell. The recent discovery that the metabolite cargo of dead and dying cells ingested through efferocytosis by macrophages can alter metabolic pathways and downstream function of the efferocyte is markedly changing the way we think about macrophage immunometabolism. Metabolic transitions of macrophages contribute to their functions in all stages of atherosclerosis, from lesion initiation to formation of advanced lesions characterized by necrotic cores, to lesion regression following aggressive lipid lowering. This review article discusses recent advances in our understanding of these different aspects of macrophage immunometabolism in atherosclerosis. With the increasing understanding of the roles of macrophage immunometabolism in atherosclerosis, new exciting concepts and potential targets for intervention are emerging.

Neutrophils in innate immunity and systems biology-level approaches

The innate immune system is the first line of host defense against invading microorganisms. Polymorphonuclear leukocytes (PMNs or neutrophils) are the most abundant leukocyte in humans and essential to the innate immune response against invading pathogens. Compared to the acquired immune response, which requires time to develop and is dependent on previous interaction with specific microbes, the ability of neutrophils to kill microorganisms is immediate, nonspecific, and not dependent on previous exposure to microorganisms. Historically, studies of PMN-pathogen interaction focused on the events leading to killing of microorganisms, such as recruitment/chemotaxis, transmigration, phagocytosis, and activation, whereas postphagocytosis sequelae were infrequently considered. In addition, it was widely accepted that human neutrophils possessed limited capacity for new gene transcription and thus, relatively little biosynthetic capacity. This notion has changed dramatically within the past 20 years. Further, there is now more effort directed to understand the events occurring in PMNs after killing of microbes. Herein, we give an updated review of the systems biology-level approaches that have been used to gain an enhanced view of the role of neutrophils during host-pathogen interaction and neutrophil-mediated diseases. We anticipate that these and future systems-level studies will continue to provide information important for understanding, treatment, and control of diseases caused by pathogenic microorganisms. This article is categorized under: Physiology > Organismal Responses to Environment Physiology > Mammalian Physiology in Health and Disease Biological Mechanisms > Cell Fates.

A bacterial sulfonolipid triggers multicellular development in the closest living relatives of animals

Bacterially-produced small molecules exert profound influences on animal health, morphogenesis, and evolution through poorly understood mechanisms. In one of the closest living relatives of animals, the choanoflagellate Salpingoeca rosetta, we find that rosette colony development is induced by the prey bacterium Algoriphagus machipongonensis and its close relatives in the Bacteroidetes phylum. Here we show that a rosette inducing factor (RIF-1) produced by A. machipongonensis belongs to the small class of sulfonolipids, obscure relatives of the better known sphingolipids that play important roles in signal transmission in plants, animals, and fungi. RIF-1 has extraordinary potency (femtomolar, or 10(-15) M) and S. rosetta can respond to it over a broad dynamic range-nine orders of magnitude. This study provides a prototypical example of bacterial sulfonolipids triggering eukaryotic morphogenesis and suggests molecular mechanisms through which bacteria may have contributed to the evolution of animals.DOI:http://dx.doi.org/10.7554/eLife.00013.001.

Gene expression pattern in swine neutrophils after lipopolysaccharide exposure: a time course comparison

Background

Experimental exposure of swine neutrophils to bacterial lipopolysaccharide (LPS) represents a model to study the innate immune response during bacterial infection. Neutrophils can effectively limit the infection by secreting lipid mediators, antimicrobial molecules and a combination of reactive oxygen species (ROS) without new synthesis of proteins. However, it is known that neutrophils can modify the gene expression after LPS exposure. We performed microarray gene expression analysis in order to elucidate the less known transcriptional response of neutrophils during infection.

Methods

Blood samples were collected from four healthy Iberian pigs and neutrophils were isolated and incubated during 6, 9 and 18 hrs in presence or absence of lipopolysaccharide (LPS) from Salmonella enterica serovar Typhimurium. RNA was isolated and hybridized to Affymetrix Porcine GeneChip^®. Microarray data were normalized using Robust Microarray Analysis (RMA) and then, differential expression was obtained by an analysis of variance (ANOVA).

Results

ANOVA data analysis showed that the number of differentially expressed genes (DEG) after LPS treatment vary with time. The highest transcriptional response occurred at 9 hr post LPS stimulation with 1494 DEG whereas at 6 and 18 hr showed 125 and 108 DEG, respectively. Three different gene expression tendencies were observed: genes in cluster 1 showed a tendency toward up-regulation; cluster 2 genes showing a tendency for down-regulation at 9 hr; and cluster 3 genes were up-regulated at 9 hr post LPS stimulation. Ingenuity Pathway Analysis revealed a delay of neutrophil apoptosis at 9 hr. Many genes controlling biological functions were altered with time including those controlling metabolism and cell organization, ubiquitination, adhesion, movement or inflammatory response.

Conclusions

LPS stimulation alters the transcriptional pattern in neutrophils and the present results show that the robust transcriptional potential of neutrophils under infection conditions, indicating that active regulation of gene expression plays a major role in the neutrophil-mediated- innate immune response.

FURTHER STUDIES ON IMMUNITY IN EXPERIMENTAL CRYPTOCOCCOSIS

Following infection with 10³ cells of Cryptococcus neoformans, progressive multiplication occurred in all tissues for 7 to 28 days. Thereafter, most mice gained control of the infection so that 3 to 6 months after inoculation, tissues were usually sterile or contained only small numbers of cryptococci. Survivors challenged 1 to 4 months after infection with 10³ cells lived longer than controls and had an increased survival rate. Pretreatment with bacterial endotoxin also resulted in protection against cryptococcal challenge. Endotoxin-protected animals showed no ability to limit the infection until circulating antibody could be demonstrated. Histologic studies revealed an increased cellular infiltration in the brains of specifically protected and endotoxin-protected mice 1 to 2 weeks after challenge. However, control of cryptococcal multiplication could be correlated with the presence of antibody but could not be correlated with the enhanced cellular response. Although protection against cryptococcal challenge appears to be antibody-dependent, it is unclear whether protective antibody is to be found in plasma or is tissue-bound.

STUDIES ON THE EFFECT OF CERTAIN MACROMOLECULAR SUBSTANCES ON THE RESPIRATORY ACTIVITY OF THE LEUCOCYTES OF PERIPHERAL BLOOD

The oxygen, uptake of lightly heparinized human blood was found to increase markedly upon the addition of bacterial endotoxins, soluble antigen-antibody complexes, or polystyrene latex particles. The effect apparently reflects a transitory stimulation of respiratory activity of the blood leucocytes. The effect did not occur in the presence of anticoagulant amounts of citrate or ethylenediaminetetraacetate, was inhibited by iodoacetate and fluoride ions, and may be related to the energy-yielding processes involved in histamine release or phagocytosis.

Role of neutrophils in innate immunity: a systems biology-level approach

The innate immune system is the first line of host defense against invading microorganisms. Polymorphonuclear leukocytes (PMNs or neutrophils) are the most abundant leukocyte in humans and essential to the innate immune response against invading pathogens. Compared with the acquired immune response, which requires time to develop and is dependent on previous interaction with specific microbes, the ability of neutrophils to kill microorganisms is immediate, non-specific, and not dependent on previous exposure to microorganisms. Historically, studies on PMN-pathogen interaction focused on the events leading to killing of microorganisms, such as recruitment/chemotaxis, transmigration, phagocytosis, and activation, whereas post-phagocytosis sequelae were infrequently considered. In addition, it was widely accepted that human neutrophils possessed limited capacity for new gene transcription and thus, relatively little biosynthetic capacity. This notion has changed dramatically within the past decade. Further, there is now more effort directed to understand the events occurring in PMNs after killing of microbes. Herein we review the systems biology-level approaches that have been used to gain an enhanced view of the role of neutrophils during host-pathogen interaction. We anticipate that these and future systems-level studies will ultimately provide information critical to our understanding, treatment, and control of diseases caused by pathogenic microorganisms.

Leukocyte glycolysis and lactate output in animal sepsis and ex vivo human blood

Lactate is released in large quantity from sites of sepsis and inflammation. We asked whether the increased lactate production found in sepsis can be explained by the augmented glycolysis of inflammatory cells. The glycolytic metabolism of rat peritoneal leukocytes was measured following cecal ligation and perforation (CLP) or sham laparotomy. CLP augmented glucose uptake, the pentose phosphate pathway, and glucose oxidation. Lactate output increased from 1.03 +/- 0.05 to 1.20 +/- 0.05 fmol x cell(-1) x min(-1) (P < .001). Total lactate output of peritoneal lavage fluid increased from 7.94 +/- 2.59 to 28.12 +/- 5.60 nmol L x min(-1) (P < .005). The effect of lipopolysaccharide (LPS) on the lactate output of whole blood from 31 critically ill patients was measured. Leukocyte lactate production was calculated by multiple linear regression analysis. Following exposure to LPS, human leukocyte lactate output increased from 0.20 +/- 0.09 to 1.22 +/- 0.14 fmol x cell(-1) x min(-1) (P < .001). This rate of production is so high that it suggests that the lactate output of different tissue beds in sepsis may be affected by their different cell populations and state of activation. This study supports the hypothesis that lactate may be more a product of inflammation than a marker of tissue hypoxia in sepsis.

In vitro effects of C-reactive protein on phagocytosis

Hokama, Y. (University of California, Los Angeles), Monroe K. Coleman, and Richard F. Riley. In vitro effects of C-reactive protein on phagocytosis. J. Bacteriol. 83:1017-1024. 1962. Carbonyl iron spherules, Diplococcus pneumoniae types IIs and XXVIIs, and Serratia marcescens were phagocytosed more rapidly and in greater numbers by leukocytes of normal human blood after incubation with C-reactive protein. With the exception of carbonyl iron spherules, addition of C-reactive protein to whole blood containing substrate had little effect on the extent of phagocytosis. Normal and acute-phase seromucoid Escherichia coli lipopolysaccharide and crude endogenous pyrogen were without a stimulating effect under the same conditions in the homologous systems employed.

Degranulation of polymorphonuclear leucocytes following phagocytosis of microorganisms

A marked reduction in numbers of cytoplasmic granules in rabbit and human polymorphonuclear leucocytes takes place following ingestion of various microorganisms or of a yeast cell wall preparation. The degranulation occurs within 30 minutes of phagocytosis, and is directly related to the quantity of material engulfed. White cells completely degranulated following phagocytosis of large numbers of microorganisms remain viable for at least 1 hour. The granules of polymorphonuclear leucocytes contain the antimicrobial agent, phagocytin, and various digestive enzymes. These substances thus are released into the cytoplasm or into vacuoles following ingestion of foreign material. The granule system and granule lysis mechanism may well play a central role in the primary function of these specialized cells; namely, that of destroying invading microorganisms.

Effect of endotoxin on cells and on their response to infection by polioviruses

Murphy, W. H. (The University of Michigan, Ann Arbor) and C. Wisner. Effect of endotoxin on cells and on their response to infection by polioviruses. J. Bacteriol. 83:649-662. 1962.-The effect of lipopolysaccharide on HeLa-S3, HeLa-Gey, Chang-liver, Maben, and L strain mouse fibroblasts was studied. The liminal dose of endotoxin for the human epithelial cell strains was approximately 250 mug/ml, and their order of sensitivity to endotoxin was: Chang-liver, HeLa-Gey, HeLa-S3, and Maben, the latter being the most resistant. Endotoxin at concentrations exceeding 100 mug/ml was cytotoxic to the L strain of mouse fibroblasts and caused them to markedly agglutinate. Cytotoxic response of cells to endotoxin was not characterized by cell lysis, but by distinctive nuclear changes. In an attempt to demonstrate the metabolic induction of the latent infection of cell cultures by a noncytopathic variant of poliovirus, endotoxin was added at maximal subliminal concentration to cell cultures totally, partially, or fully susceptible to virus. Endotoxin caused a slight but consistent accelerative cytopathic response of cells to infection by cytopathic poliovirus, but failed to induce cytopathic response to infection by submoderate (noncytopathic) poliovirus. Although endotoxin slightly suppressed yields of poliovirus from cells, it did not affect the plating efficiency of virus on cell monolayers.

The fate of bacteria within phagocytic cells. II. The modification of intracellular degradation

The influence of immune serum, PMN leucocytes, and macrophages from immunized animals and metabolic inhibitors on the intraphagocytic degradation of isotopically labeled bacteria has been evaluated. Immune serum specifically delayed the degradation of a variety of P(32)- and C(14)-labeled organisms within both types of phagocytic cells. The active principle in immune serum was found to be a globulin which could be removed by adsorption with the homologous organism. The inhibiting action of immune serum was thought to be related to its combination with the bacterial surface and the subsequent temporary protection of the bacteria from leucocyte enzymes. PMN leucocytes and macrophages obtained from immune hosts did not differ from normal cells in their ability to degrade homologous, labeled bacteria. Immune serum had the same inhibiting influence in the presence of "immune" cells as with cells from non-immunized hosts. Iodoacetate, arsenite, and cyanide at concentrations which inhibited the glycolysis and respiration of both PMN leucocytes and macrophages had no influence on the rate of degradation of isotopically labeled bacteria engulfed by these cells. This implied that following the initial phagocytic events, the degradation of bacteria within leucocytes is not dependent upon the major pathways of energy metabolism.

Structure and development of viruses as observed in the electron microscope. V. Western equine encephalomyelitis virus

Stages in the development and release of Western equine encephalomyelitis virus are illustrated and described. It is suggested that precursor particles 22 mmicro in diameter differentiate at template sites close to membranes bordering cytoplasmic vacuoles and that these particles either pass into the lumen of the vacuole, acquiring in the process a coat and peripheral membrane, or are dispersed in the cytoplasm and extruded through the cellular wall, emerging as viral particles on the surface. Although necrosis and dissolution of the cell with release of contents, including virus, may intervene at any stage of infection, ejection of virus from the vacuoles presumably can occur without rupture of the cell. The virus consists of a 30 mmicro core separated by a zone of lesser density from a sharply defined peripheral membrane 45 to 48 mmicro in diameter. Precursor particles, as well as viral particles, occasionally crystallize, the former in the cytoplasm, the latter in vacuoles and probably on the cellular surface.

The effect of bacterial endotoxins on the water intake and body weight of mice

Injection of endotoxin of Gram-negative bacilli into NCS mice caused an immediate reduction or interruption of water intake by these animals, with a resultant loss of body weight. Endotoxins prepared by three different techniques from four different cultures of Gram-negative bacilli yielded products having approximately the same activity in inhibiting water intake. The minimum effective dose was 0.1 µg. or less. With all toxin preparations tested, the duration of the effect was directly related to the dose injected. The heat-killed cells of Esch. coli proved approximately as effective as the endotoxins prepared from Gram-negative bacilli. In contrast, heat-killed cells of Mycobacterium tuberculosis (BCG) were much less active, and heat-killed cells of Staphylococcus aureus were essentially inactive. Mice previously treated with endotoxin exhibited a marked degree of tolerance to the inhibition of water intake caused in normal animals by a subsequent treatment with the same material. Tolerance could also be induced by vaccination with heat-killed Gram-negative bacilli. Tolerance overlapped from one bacterial species to another but was more pronounced toward the endotoxin prepared from the bacterial culture with which the animal was vaccinated. The duration of the inhibitory effect of endotoxin on water intake was much shorter with mice fed a complete diet than with mice fed a deficient diet (corn). It took approximately the same dose of endotoxin (0.1 µg.) to inhibit water intake, reduce the influx of polymorphonuclear leucocytes, and enhance staphylococcal infection.

Studies on the pathogenesis of staphylococcal infection. IV. The effect of bacterial endotoxin

Intracutaneous and intravenous injection of pyrogenic, non-lethal doses of bacterial endotoxin were found to increase the infectivity of pathogenic but not non-pathogenic staphylococci in rabbit skin. The increased infectivity of the microorganism was characterized by accelerated multiplication at the site of inoculation and by the production of necrosis and hemorrhage locally. Histologically, the infection of skin in endotoxin-prepared animals was characterized by necrosis, masses of bacteria, but absence of leukocytic infiltration into the area of bacterial growth. The infectivity of staphylococci in skin of endotoxin-prepared rabbits could be controlled by antibody to the alpha hemolysin of the microorganism. The effect of endotoxin upon staphylococcal infection was demonstrable only within 4 hours after injection of the endotoxin. It could not be prevented with chlorpromazine or dibenamine and was closely related to the effect of endotoxin upon leukocytes. It was suggested that the effect of endotoxin upon leukocytes was probably responsible for its influence upon staphylococcal infection. The implications of these findings in the pathogenesis of staphylococcal infection are discussed.

The correlation of a biphasic metabolic response with a biphasic response in resistance to tuberculosis in rabbits

We have found a phase of susceptibility associated with a reduced metabolic activity on the part of peritoneal mononuclear phagocytes taken from BCG-vaccinated rabbits. A second stage of heightened resistance to infection was found to be associated with a heightened metabolic activity. The period of susceptibility in BCG vaccination is primarily concerned with initiation of the infection and not with the progression of the disease, which in both stages is increased. These reactions are discussed in relation to other conditions, such as nonspecific protein therapy and the administration of endotoxin, which also have similiar biphasic stages of resistance. Of incidental interest is the fact that rabbits who received 400 roentgen units are two years later still unable to respond to BCG vaccination with an increase in resistance. We conclude that there is a relationship between the level of certain metabolic activities of reticuloendothelial cells and resistance to tuberculosis.

Lymphokine-augmented activation of avian heterophils

Heterophils are important mediators of innate resistance in poultry, especially in young birds that have not yet developed an acquired immune response. Invasion of the intestinal mucosa by Salmonella spp. initiates the recruitment of large numbers of heterophils to the lamina propria. Thus, the heterophilic response can control, but not eliminate, bacterial numbers in the bird until development of acquired immunity. Unfortunately, chicks and turkey poults are highly susceptible to Salmonella infections during the first 4 d posthatch due to the functional immaturity of both the innate and acquired immune systems. We have previously shown that the administration of Salmonella enteritidis (SE)-immune lymphokines (ILK) into either 18-d-old developing embryos or day-of-hatch chicks and poults conferred increased resistance to SE organ invasion. In this review, we present evidence that the protection induced by ILK is mediated by vigorous recruitment and activation of heterophils. These activated heterophils migrate rapidly to the site of bacterial invasion where they phagocytize and kill the SE. Specifically, in vitro studies demonstrate an enhancement of functional activities of the heterophils including chemotaxis, adherence, phagocytosis, and bacterial killing. In addition, during the activation process, membrane expression of adhesion molecules rapidly changes from L-selectins to beta2 integrins (CB11b/CD18) on the cells that become activated. These results further demonstrate the validity of preventive activation in poultry to induce the migration of large numbers of activated phagocytic cells to the site of infection by a pathogenic organism. Importantly, this immunopotentiation of the inflammatory response by ILK, as described here, induces the functional maturation of heterophils during the first 4 d posthatch.

Effects of adenosine on the functions of circulating polymorphonuclear leukocytes during hyperdynamic endotoxemia

Endotoxin-activated polymorphonuclear leukocytes (PMNL) adhere to the vascular endothelium and cause damage by the release of toxic superoxide anions (O2-). Because adenosine is a potent inhibitor of PMNL in vitro, the present study investigates the effects of this nucleoside on the functions of circulating PMNL in a standardized porcine model of hyperdynamic endotoxemia. Ten anesthesized pigs received an intravenous (i.v.) 330-min infusion of endotoxin (5 microg/kg of body weight per h). Another 10 pigs were also infused with endotoxin plus adenosine (150 microg/kg/min [i.v.]); this treatment was begun 30 min prior to the beginning of endotoxin treatment. Control groups (five animals per group) received either adenosine or physiological saline. Infusion of endotoxin caused severe neutropenia, shedding of L-selectin, upregulation of beta2-integrins, increased binding of C3-coated zymosan particles, and subsequent phagocytosis by PMNL. While phagocytosis-induced production of oxygen radicals appeared to decrease, extracellular release of superoxide anions was strongly enhanced. Infusion of adenosine during endotoxemia had no effect on neutropenia, expression of adhesion molecules, C3-induced adhesion, phagocytosis, or intracellular production of oxygen radicals, whereas extracellular release of O2- was strongly inhibited. Thus, i.v. infusion of adenosine during endotoxemia could be useful in protecting from O2(-)-mediated tissue injury without compromising the bactericidal mechanisms of PMNL.

Zanvil Alexander Cohn 1926-1993

Zanvil Alexander Cohn, an editor of this Journal since 1973, died suddenly on June 28, 1993. Cohn is best known as the father of the current era of macrophage biology. Many of his scientific accomplishments are recounted here, beginning with seminal studies on the granules of phagocytes that were performed with his close colleague and former editor of this Journal, James Hirsch. Cohn and Hirsch identified the granules as lysosomes that discharged their contents of digestive enzymes into vacuoles containing phagocytosed microbes. These findings were part of the formative era of cell biology and initiated the modern study of endocytosis and cell-mediated resistance to infection. Cohn further explored the endocytic apparatus in pioneering studies of the mouse peritoneal macrophage in culture. He described vesicular inputs from the cell surface and Golgi apparatus and documented the thoroughness of substrate digestion within lysosomal vacuoles that would only permit the egress of monosaccharides and amino acids. These discoveries created a vigorous environment for graduate students, postdoctoral fellows, and junior and visiting faculty. Some of the major findings that emerged from Cohn's collaborations included the radioiodination of the plasma membrane for studies of composition and turnover; membrane recycling during endocytosis; the origin of the mononuclear phagocyte system in situ; the discovery of the dendritic cell system of antigen-presenting cells; the macrophage as a secretory cell, including the release of proteases and large amounts of prostaglandins and leukotrienes; several defined parameters of macrophage activation, especially the ability of T cell-derived lymphokines to enhance killing of tumor cells and intracellular protozoa; the granule discharge mechanism whereby cytotoxic lymphocytes release the pore-forming protein perforin; the signaling of macrophages via myristoylated substrates of protein kinase C; and a tissue culture model in which monocytes emigrate across tight endothelial junctions. In 1983, Cohn turned to a long-standing goal of exploring host resistance directly in humans. He studied leprosy, focusing on the disease site, the parasitized macrophages of the skin. He injected recombinant lymphokines into the skin and found that these molecules elicited several cell-mediated responses. Seeing this potential to enhance host defense in patients, Cohn was extending his clinical studies to AIDS and tuberculosis. Zanvil Cohn was a consummate physician-scientist who nurtured the relationship between cell biology and infectious disease.(ABSTRACT TRUNCATED AT 400 WORDS)

Expression of interleukin-1 receptor antagonist (IL-1ra) by human circulating polymorphonuclear cells

After appropriate stimulation, mononuclear phagocytes express a specific inhibitor of interleukin (IL)-1, now re-named IL-1 receptor antagonist (IL-1ra). In this study we have examined the production of IL-1ra by polymorphonuclear cells (PMN). Human PMN isolated from peripheral blood expressed low but detectable levels of IL-1ra transcripts, which were considerably augmented after treatment with lipopolysaccharides (LPS) and cytokines [IL-4, granulocyte (G)- and granulocyte macrophage (GM)-Colony Stimulating factor (CSF), and tumor necrosis factor (TNF)]. The levels of induced IL-1 ra transcripts were comparable to those observed in endotoxin-stimulated human monocytes. By contrast IL-1 beta, interferon (IFN)-gamma and chemotactic factors (fMLP, C5a and IL-8) failed to promote IL-1ra expression in PMN. IL-1ra induction by LPS reached peak levels at 10 ng/ml after 3-6 h and remained sustained 24 h after stimulation. Induction by LPS and GM-CSF appears to be at the transcriptional level, as assessed by inhibiting mRNA synthesis with actinomycin D. Inhibition of protein synthesis by cycloheximide superinduced both basal and inducible IL-1ra mRNA. In addition to expressing mRNA, PMN also produce IL-1ra protein. Secretion of IL-1ra was induced in PMN treated with LPS, IL-4 and GM-CSF, but not by IL-1 beta, IFN-gamma and fMLP, thus yielding results that paralleled those seen in Northern blot experiments. These data indicate that, among myelomonocytic cells, PMN, in addition to mononuclear phagocytes, can express IL-1ra, suggesting that PMN, while exerting a series of pro-inflammatory activities, may also modulate the inflammatory potential of IL-1 in tissues.

The secretion of the third component of complement (C3) by human polymorphonuclear leucocytes from both normal and systemic lupus erythematosus cases

Recently, murine peritoneal exudate polymorphonuclear leucocytes (PMNs) have been proved to secrete complement C3. In this report we show the secretion of C3 by normal human blood PMNs. ELISA assay was used to detect secreted C3 in culture supernatants of PMNs, while immunoperoxidase staining was used for intracellular C3 detection. 12-o-tetradecanoyl phorbol 13 acetate (TPA) had a flushing effect on C3 secretion by PMNs but not macrophages, suggesting a special C3 storing capability in PMNs. Dioctanoyl glycerol, mezerein and calcium ionophore A23187 caused the same marked increase in C3 secretion by PMNs. This suggests the contribution of protein kinase C and the calmodulin pathway in the mechanism of C3 secretion, similar to murine peritoneal exudate PMNs. In some cases of systemic lupus erythematosus, C3 secretion by blood PMNs was increased but no similar response to TPA could be detected.

Neutrophil adherence induced by lipopolysaccharide in vitro. Role of plasma component interaction with lipopolysaccharide

Endotoxemia results in neutrophil localization within a number of microcirculatory beds, reflecting in part an adhesive interaction between neutrophils and the vascular endothelial cell. In previous studies, endotoxin or lipopolysaccharide (LPS) treatment of rabbits resulted in neutrophil sequestration at LPS concentrations well below those effective at increasing neutrophil adherence in vitro. We hypothesized that LPS-induced neutrophil adherence involved a plasma component. In the absence of plasma, high concentrations of LPS (10 micrograms/ml) were required to increase human neutrophil adherence to endothelial cells in vitro. With the inclusion of as little as 1% plasma or serum, however, the LPS dose-response curve was markedly shifted, resulting in increments in adherence at 10 ng/ml, and the time course of enhanced adherence was accelerated. Pretreatment studies suggested that the effect of LPS was on the neutrophil rather than the endothelial cell. Immunoprecipitation of 0111:B4 LPS paralleled the loss of functional activity, suggesting that LPS was an integral part of the active complex, rather than altering a plasma component to make it active. The incubation of plasma with LPS decreased the apparent molecular mass of LPS from 500-1,000 kD to approximately 100 kD. The disaggregated 0111:B4 LPS eluted in the range of albumin and was able to increase adherence in the absence of additional plasma. Plasma depleted of lipoproteins or heat treated retained activity, suggesting that the interaction of LPS with HDL or complement did not account for the observed findings. An LPS-binding protein isolated from rabbit serum enhanced the adherence-inducing effects of both 0111:B4 and Re595 LPS. Furthermore, the activity of rabbit serum was abolished after incubation with an antibody directed against this LPS-binding protein (LBP). An antibody directed against CD14, the putative receptor of the LPS-LBP complex, prevented the adhesive response to LPS. These data suggest that LPS is disaggregated by an LBP in serum and plasma to form an active LPS-plasma component complex. This putative complex then interacts with CD14 on the neutrophil so as to induce an adhesive state.

Lactoferrin release and interleukin-1, interleukin-6, and tumor necrosis factor production by human polymorphonuclear cells stimulated by various lipopolysaccharides: relationship to growth inhibition of Candida albicans

Lipopolysaccharides (LPSs) from Escherichia coli, Serratia marcescens, and Salmonella typhimurium, at doses from 1 to 100 ng/ml, strongly enhanced growth inhibition of Candida albicans by human polymorphonuclear leukocytes (PMN) in vitro. Flow cytometry analysis demonstrated that LPS markedly augmented phagocytosis of Candida cells by increasing the number of yeasts ingested per neutrophil as well as the number of neutrophils capable of ingesting fungal cells. LPS activation caused augmented release of lactoferrin, an iron-binding protein which itself could inhibit the growth of C. albicans in vitro. Antibodies against lactoferrin effectively and specifically reduced the anti-C. albicans activity of both LPS-stimulated and unstimulated PMN. Northern (RNA blot) analysis showed enhanced production of mRNAs for interleukin-1 beta, tumor necrosis factor alpha, and interleukin-6 and in neutrophils within 1 h of stimulation with LPS. The cytokines were also detected in the supernatant of the activated PMN, and their synthesis was prevented by pretreatment of LPS-stimulated PMN with protein synthesis inhibitors, such as emetine and cycloheximide. These inhibitors, however, did not block either lactoferrin release or the anti-Candida activity of LPS-stimulated PMN. These results demonstrate the ability of various bacterial LPSs to augment neutrophil function against C. albicans and suggest that the release of a candidastatic, iron-binding protein, lactoferrin, may contribute to the antifungal effect of PMN. Moreover, the ability to produce cytokines upon stimulation by ubiquitous microbial products such as the endotoxins points to an extraphagocytic, immunomodulatory role of PMN during infection.

Septin: a factor in plasma that opsonizes lipopolysaccharide-bearing particles for recognition by CD14 on phagocytes

We have previously reported that lipopolysaccharide (LPS) binding protein (LBP) opsonizes endotoxin (LPS) for recognition by CD14 on phagocytes. Here we show that normal human plasma contains high titers of an activity that also binds LPS (Re, 595) and mediates recognition by CD14. Opsonization of LPS-coated particles with plasma enables the particles to be bound by phagocytes. Further, opsonization with plasma also enables subnanogram-per-milliliter concentrations of LPS to induce dramatic alterations in the function of leukocyte integrins on polymorphonuclear leukocytes and to induce secretion of tumor necrosis factor by monocytes, suggesting that opsonization by factors in plasma may be important in responses of cells to endotoxin. The opsonic activity in plasma appears distinct from LBP since it is not blocked by neutralizing antibodies against LBP. Surprisingly, the opsonic activity of plasma is not present in a single protein species, but at least two species must be combined to observe activity. Further, the opsonic activity of plasma for LPS is blocked by addition of protease inhibitors, suggesting that proteolytic activity or activities are required for opsonization. These properties are suggestive of the action of a protease cascade, but opsonic activity of plasma is not affected by blockade or depletion of either the complement or clotting cascades. We propose the name "septin" to describe this novel LPS-opsonizing activity in plasma.

Activation of the adhesive capacity of CR3 on neutrophils by endotoxin: dependence on lipopolysaccharide binding protein and CD14

Tumor necrosis factor alpha, granulocyte colony-stimulating factor, granulocyte/macrophage colony-stimulating factor, and formyl peptide were each found to cause a twofold increase in expression of CD14 on the surface of polymorphonuclear leukocytes (PMN). Upregulation of CD14 was complete by 20 min and thus appeared to result from expression of preformed stores of protein. The CD14 on the surface of PMN was shown to serve two biological functions. It bound particles coated with complexes of lipopolysaccharide (LPS) and LPS binding protein (LBP). This binding activity was enhanced by agonists that upregulated CD14 expression and may serve in the clearance of Gram-negative bacteria opsonized with LBP. Interaction of CD14 with LPS in the presence of LBP or serum also caused a dramatic, transient increase in the adhesive activity of CR3 (CD11b/CD18) on PMN. Enhanced activity of CR3 and other members of the CD11/CD18 family underlies many of the known physiological responses of PMN to LPS and may be a central feature of the in vivo responses of PMN to endotoxin.

Cerebrospinal fluid lactate in 78 cases of adult meningitis

In a retrospective study of 78 cases of adult meningitis, the CSF lactate was measured on the first spinal tap (ST); 25 had a bacterial meningitis, 28 a viral meningitis; 22 other cases had been on antibiotics prior to admission; 3 cases had meningitis of rare aetiology. The median CSF lactate level among the 25 bacterial cases amounted to 13.6 mmol/l (range: 3.5-24.5) whereas it remained low in the 28 viral cases: 2.7 mmol/l (range: 1.4-4.2). These differences are highly significant. The comparison of the CSF lactate level with the other tests routinely performed showed that the CSF lactate level had the highest sensitivity, specificity and predictive values. The CSF lactate level on the first ST had no prognostic value, but a rapid decrease of the CSF lactate during the treatment is indicative of good prognosis. Among the pretreated cases, a high lactate level could be an indication that bacteria were the causal agents. In conclusion, the measurement of the CSF lactate, quickly performed and inexpensive, is worth performing when a meningitis is suspected, as it appears to be the best way of distinguishing bacterial from non-bacterial meningitis.

Endotoxaemia in patients with Crohn's disease: a longitudinal study of elastase/alpha 1-proteinase inhibitor and Limulus-amoebocyte-lysate reactivity

During intensive care, the severity of gut-derived systemic endotoxaemia in 16 patients with active Crohn's disease was characterized by the simultaneous determination of elastase/alpha 1-proteinase-inhibitor and Limulus-amoebocyte-lysate-reactivity. Using both assays in 15/16 patients the detectable endotoxic activity during the disease course was reflected by a parallelism between elastase/alpha 1-proteinase-inhibitor and Limulus-amoebocyte-lysate-reactivity. In 8 gut-irrigated patients, significantly lower elastase/alpha 1-proteinase-inhibitor concentrations and Limulus-amoebocyte-lysate-reactivities were measured compared with 8 gut-nonirrigated patients. The Crohn's disease activity index and the van Hees activity index as well as the inpatient time were significantly lower in lavage patients compared with gut-nonirrigated patients. It is concluded with that elastase/alpha 1-proteinase-inhibitor can be used as an alternative to the bioassayed Limulus-amoebocyte-lysate-reactivity in order to characterize systemic endotoxaemia.

Phagocyte-derived lactate stimulates oxygen consumption by Neisseria gonorrhoeae. An unrecognized aspect of the oxygen metabolism of phagocytosis

O2 consumption resulting from interaction of Neisseria gonorrhoeae and human neutrophils represents a composite of O2 consumed by the two cell systems. Experiments studying the relative contribution of each system suggested the possibility that gonococci increased their metabolic activity in response to interaction with neutrophils. This hypothesis was confirmed by demonstrating that undifferentiated HL-60 cells, which are unable to undergo a respiratory burst, induce a two- to three-fold increase in gonococcal O2 consumption. Gonococcal capacity to adhere to HL-60 cells did not correlate with extent of metabolic stimulation. Stimulatory activity was demonstrable in cell-free supernatant from neutrophils or HL-60 cells, and increased with duration of incubation. Supernatant applied to a G-15 Sephadex column yielded fractions that stimulated gonococcal O2 consumption. Elution profiles were similar for HL-60 cells, neutrophils, and a stimulatory factor previously isolated from pooled human serum. This stimulatory factor(s) failed to adhere to DEAE or C-18 HPLC columns. Stimulatory activity release from myeloid cells was inhibited by incubation at 4 degrees C or in the presence of NaF, indicating a critical role for glucose metabolism. Lactate, the principal product of resting neutrophil glucose catabolism, was demonstrable in cell-free supernatants after incubation at 37 degrees C. Lactate accumulation was inhibited by NaF and decreased temperature of incubation. Lactate at levels present in cell-free supernatant increased gonococcal O2 consumption twofold and restored stimulatory activity to dialyzed serum. Live, but not heat-killed gonococci eliminated lactate released from neutrophils during phagocytosis. Gonococci are able to utilize host-derived lactate to enhance their rate of O2 metabolism.

The pulmonary vascular sequestration of neutrophils in endotoxemia is initiated by an effect of endotoxin on the neutrophil in the rabbit

Endotoxemia causes neutrophil sequestration in the pulmonary vascular bed. Such sequestration may be a critical initiating event in the generation of microvascular injury, although the mechanisms that lead to this localization are not understood. To investigate these phenomena, the following study employed intravenous pulses of 111Indium-tropolonate-labeled neutrophils (111In-neutrophils), which circulated in the rabbit with normal kinetics and responded in a manner indistinguishable from unlabeled, circulating neutrophils in response to an intravenous injection of purified endotoxic lipopolysaccharide (LPS) or epinephrine. Pulmonary sequestration of 111In-neutrophils was assessed by quantitative external gamma camera scintigraphy of a lung suprahilar region of interest. Noninvasive assessment of radioactivity by this method accurately reflected total lung radioactivity, which was shown by autoradiography to be confined to the injected 111In-neutrophils. Intravenously administered LPS caused a marked, dose-dependent sequestration of 111In-neutrophils in the pulmonary vasculature, and exhaustive ultrastructural autoradiography showed discretely radiolabeled neutrophils located within pulmonary capillaries. A distinct effect was seen with an intravenous injection of as little as 100 ng per rabbit (i.e., 500 pg/ml blood). A 5-min ex vivo pretreatment of 111In-neutrophils with 10 ng to 10 micrograms/ml LPS in heat-inactivated plasma (which resulted in retention of as little as 500 pg LPS per 10(7) neutrophils) also caused dose-dependent pulmonary sequestration of the pretreated 111In-neutrophils but did not cause generalized neutropenia in recipient rabbits. There was no evidence of complement activation on the surface of pretreated neutrophils.(ABSTRACT TRUNCATED AT 250 WORDS)

Down-modulation of receptors for granulocyte colony-stimulating factor on human neutrophils by granulocyte-activating agents

Purified human blood neutrophils were able to bind radioiodinated murine granulocyte-colony-stimulating factor (G-CSF) in a specific manner. This factor has previously been shown to stimulate functional activities of human and murine neutrophilic granulocytes and to be functionally analogous to human-derived CSF beta. The binding of 125I G-CSF to human neutrophils was competed for equally by unlabeled G-CSF and CSF beta but not by other CSF's. Saturation analysis indicated that human neutrophils displayed about 700-1,500 receptors for G-CSF/CSF beta per cell. Three other agents (N-formyl-methionine-leucine phenylalanine, bacterial lipopolysaccharide, and human CSF alpha) known to activate neutrophils did not compete directly for G-CSF binding sites but, in preincubation experiments at 37 degrees C, were able to down-modulate the expression of G-CSF receptors on human neutrophils in a dose- and time-dependent manner. This effect was specific since the same agents have been shown elsewhere to up-regulate the expression of other granulocyte surface antigens and other agents were much less effective at down-modulating G-CSF receptors. Since the granulocyte-activating agents increase the sensitivity of human neutrophils to G-CSF/CSF beta and mimic some of the actions of G-CSF on neutrophils, it is suggested that G-CSF receptor down-modulation might be a mechanism whereby these agents activate G-CSF receptors and thereby exert some of their effects.

Bacterial clearance and granulocyte response in experimental peritonitis

Clearance kinetics of Escherichia coli and Bacteroides fragilis from the peritoneal cavity and functional properties of peritoneal and blood polymorphonuclear leukocytes (PMNL) were studied in pigs. The bacteria, approximately 10(10) colony forming units (CFU) of each species, were intraperitoneally injected. Blood and peritoneal exudate were sampled regularly during 24 hr for bacterial quantification and PMNL analysis. The peritoneal concentration of both species fell rapidly in the first 3 hr and then stabilized. Approximately 10(2) CFU/ml remained after 24 hr. Chemotaxis, phagocytosis, and metabolic activation of the peritoneal PMNL showed little change. In some pigs a second bacterial dose was injected 6 hr after the first dose and gave an identical clearance pattern. Exhaustion of the local defence capacity thus was excluded as cause of the impaired bacterial elimination.

Relationship between immune system and gram-negative bacteria. Acid-treated Salmonella minnesota R595 (Re) enhances immune responsiveness in patients with gynecologic malignancies

Nine patients with gynecologic malignancies (six cervix, two endometrium and one ovary) were injected with acid-treated Salmonella minnesota R595 (Re). Patients received a total of four injections (at increasing doses from 0.5 to 3 micrograms) every 2 weeks. All patients, before treatment, had a severe impairment of their immune system either of cell-mediated immunity (leukocyte inhibiting factor activity) or non-specific immunity (polymorphonuclear cell and/or monocyte-mediated phagocytosis and killing). In contrast, the same patients displayed a normal Natural Killer cell frequency in their peripheral blood as evaluated in an agarose-single cell cytotoxic assay. At the end of the immunotherapeutic regimen, all the above immune functions significantly augmented likely via an immunomodulating effect exerted by the lipid A portion of Salmonella minnesota Re which represents the lipopolysaccharide molecule in these bacteria. This suggests a potential role for lipid A in the treatment of cancer-related immunodeficiency.

Inhibition of in vivo neutrophil accumulation by stress. Possible role of neutrophil adherence

Psychological stress results in neural and endocrine changes which can alter various aspects of the immune system. However, the effects of stress on inflammation has not received much attention despite the fact that stress hormones, such as the corticosteroids, are known to reduce inflammation. The present study extends a previous finding that stress itself can reduce inflammation. In the first experiment, zymosan was injected into an air pouch on the dorsum of F344 rats. Half of these rats then received three hours of inescapable, intermittent, electric foot shock as a stressor. The other half of the injected rats served as nonstressed controls. A third group were given air pouches but no zymosan. Fewer neutrophils accumulated at the inflammatory site of stressed rats as compared to nonstressed control rats. However, phagocytosis of zymosan by air pouch neutrophils was higher in stressed rats. Peripheral perfusion was not altered significantly by shock, but vascular permeability was reduced in stressed rats. The effects of stress on peripheral blood leukocytes of rats not injected with zymosan was investigated. It was found that while peripheral blood monocytes and lymphocyte numbers were decreased by stress, neutrophils were not decreased. Increased neutrophil adherence was found in stressed rats. Additionally, in the presence of endotoxin, neutrophils from stressed rats did not increase their adherence as much as those of control rats. The increased adhesiveness of neutrophils in stressed animals may account for the diminished inflammatory response in the shocked rats.

Lipopolysaccharide significantly enhances erythrophagocytosis but marginally stimulates the phagocytosis of Staphylococcus aureus in mouse peritoneal macrophages

The influence of lipopolysaccharide (LPS) on phagocytic and bactericidal functions of normal mouse peritoneal macrophages was investigated. Preincubation of macrophages with LPS enhanced their capacity for phagocytosis of antibody coated sheep red blood cells 5-fold, but phagocytosis of antibody coated Staphylococcus aureus was enhanced only 1.2-ld. Phagocytosis and intracellular killing of unopsonised or normal rabbit serum opsonised S. aureus was not affected by the LPS treatment of macrophages.

Priming of neutrophils for enhanced release of oxygen metabolites by bacterial lipopolysaccharide. Evidence for increased activity of the superoxide-producing enzyme

We investigated the capacity of bacterial endotoxin (lipopolysaccharide, LPS) to modify the oxidative metabolic response to membrane stimulation of human neutrophils. Neutrophils were pretreated for 60 min with LPS, 10 ng/ml, then stimulated by exposure to fixed immune complexes, the chemotactic peptide formyl-methionyl-leucyl-phenylalanine (FMLP), or phorbol myristate acetate. Release of superoxide anion (O-2) was up to 7-times greater in cells preincubated with LPS, depending upon the stimulus used. Consumption of oxygen and release of hydrogen peroxide (H2O2) were similarly increased, using FMLP as stimulus. The enhancement was accompanied by a reduction in lag time and an increase in the rate of the response, but the duration of the oxidative events was not changed. The molecular basis for the augmented oxidative response of LPS-pretreated cells was investigated. Preincubation with LPS at 0 degrees C prevented priming, but preincubation in the presence of cycloheximide or chelation of extracellular calcium ion did not. Neutrophils preincubated with LPS had slightly decreased numbers of binding sites and equivalent binding affinity for radiolabeled FMLP. Possible changes in the enzyme responsible for the oxidative burst were analyzed by studying NADPH-dependent generation of O-2 by particulate fractions from cells preincubated with LPS or buffer, then stimulated before cell disruption. The fraction prepared from LPS-pretreated neutrophils exhibited greater release of O-2 over a wide range of concentrations of NADPH. The calculated apparent Km for NADPH was equivalent in the two fractions, but the Vmax was increased 2.5-fold in the subcellular fraction from LPS-pretreated cells. These results suggest that LPS could increase neutrophil-mediated host defense or the tissue damage associated with endotoxemia by enhancing the generation of oxygen metabolites by neutrophils. These results also support the concept that the neutrophil is not an end-stage cell in regard to function or metabolic activity.

Newer aspects of regulation of human granulocyte function

The regulation of granulocyte function by cell-derived factors is emphasised in this review. The most important of these cell-derived factors belongs to a class of substances known as colony stimulating factors (CSF) so named because they stimulate the maturation of progenitor cells into clumps or "colonies" of mature cells. CSF mediated regulation of granulocytes is likely to be important for the two reasons (i) the site of CSF production can determine the site of granulocyte activation and (ii) the type of CSF produced can determine the type of granulocyte activated. Blood mononuclear cells were found to be a good source of granulocyte activating material suggesting that interaction between these two cell types is important in vivo. The potential clinical use of CSF-like substances is discussed.

Glucose and lactate kinetics in septic rats

Glucose turnover was measured in rats subjected to experimental peritonitis. Fifteen hours following cecal ligation and puncture or sham surgery, rats were anesthetized with pentobarbital and glucose metabolism was estimated by constant infusion tracer techniques. Septic rats demonstrated significantly elevated rates of glucose appearance without any elevation of plasma glucose concentration. There was also significant hyperlactacidemia in the cecally ligated rats. The elevated plasma lactate was not accompanied by a lowering of blood pH. Arterial blood pressure were not different between groups, however the blood pressure of septic rats did fall during the infusion experiment. Septic rats demonstrated significantly elevated initial heart rates and blood hematocrit. The turnover of lactate was also elevated in the septic rats. By calculation of the relative percentage of glucose production from labeled lactate, it is obvious that septic rats had elevated rates of gluconeogenesis. Determination of plasma immunoreactive insulin indicated that septic rats were not insulin resistant.

Endotoxin-induced release of tumour necrosis factor and interferon in vivo is inhibited by prior adrenoceptor blockade

The effect of alpha- and beta-adrenoceptor blocking agents on endotoxin-induced release of tumour necrosis factor (TNF), and of interferon in the circulation of Corynebacterium parvum-treated mice was the subject of this study. TNF was quantified after injection of TNF containing heated serum (TNS) into Meth A sarcoma-bearing mice by determining colour, extent, and incidence of haemorrhagic necrosis. The release of TNF was weakly inhibited by the competitive alpha-blocker phentolamine and the beta-blocker propranolol. The non-competitive alpha-blocker phenoxybenzamine inhibited to a higher degree. Endotoxin-induced elicitation of growth-inhibiting principles into TNS was antagonized by propranolol and phenoxybenzamine. Administration of adrenaline before endotoxin inhibited the elicitation of TNF and growth-inhibitory activities, which indicates tachyphylaxis. The release of interferon was effectively inhibited by both alpha-adrenoceptor blockers but not by propranolol. The interferon was heat-labile. The results indicate that endotoxin-induced TNF and interferon are separate factors, elicited in different ways. As both alpha-blockers do not only inhibit reactions at the alpha-adrenergic receptor but also reactions at the serotonin receptor and in the case of phenoxybenzamine also at the choline receptor, it is suggested that endotoxin-induced release of the anti-tumour factors is controlled by reactions mediated by one or more of these receptors. It is suggested that the inhibition of TNF release by propranolol may be due to the membrane-stabilizing activity of this agent.

Lactate UV-system: a rapid method for diagnosis of septic arthritis

The concentration of lactic acid in synovial fluid was estimated in 43 specimens from patients with an acute monoarthritis by a simple enzyme method. In 9 patients with 10 episodes of septic arthritis concentrations of synovial fluid lactic acid were significantly higher (mean 10.8 mmol/l) than in 33 patients with nonseptic effusions (mean 3.1 mmol/l). With this method concentrations of synovial fluid lactic acid provide a rapid diagnostic guide in the separation of septic from nonseptic arthritis.

Enhanced adhesion of rat neutrophils to Litomosoides carinii microfilariae in the presence of culture supernatants from mitogen-stimulated lymph node cells

Microfilariae of the rat filarial parasite Litomosoides carinii are killed by normal rat neutrophils which adhere to them in the presence of antibody and complement. Adherence and killing were increased in the presence of the fluid from 48-hr cultures of Con A- or PHA-stimulated normal rat lymph node cells. Both normal and augmented binding were inhibited by cytochalasin B. The factor(s) responsible for increased binding was non-dialysable, susceptible to heat (56 degrees C, 30 min) and freezing and thawing. Its production was inhibited by cycloheximide. Pretreatment of neutrophils with stimulated culture supernatant for 3 hr, followed by washing, also augmented adherence. Similar pretreatment also enhanced phagocytosis of opsonized sheep erythrocytes and latex particles but did not increase candidacidal activity. These experiments suggest that cell-mediated immune reactions leading to lymphokine production may potentiate anti-filarial antibody-dependent cellular cytotoxicity and general phagocytosis by neutrophils.