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Environmental Health Perspectives Dec 1994Immune information in the form of inflammatory mediators directs phagocyte locomotion and increases expression of opsonin receptors such that contact with an opsonized... (Review)
Review
Immune information in the form of inflammatory mediators directs phagocyte locomotion and increases expression of opsonin receptors such that contact with an opsonized microbe results in receptor ligation and activation of microbicidal metabolism. Carbohydrate dehydrogenation and O2 consumption feed reactions that effectively lower the spin quantum number (S) of O2 from 1 to 1/2 and finally to 0. Oxidase-catalyzed univalent reduction of O2 (S = 1; triplet multiplicity) yields hydrodioxylic acid (HO2) and its conjugate base superoxide, O2- (S = 1/2; doublet multiplicity). Acid or enzymatic disproportionation of superoxide yields H2O2 (S = 0; singlet multiplicity). Haloperoxidase catalyzes H2O2-dependent oxidation of Cl- yielding HOCl (S = 0), and reaction of HOCl with H2O2 yields singlet molecular oxygen, 1O2 (S = 0; singlet multiplicity). The Wigner spin conservation rule restricts direct reaction of S = 1 O2 with S = 0 organic molecules. Lowering the S of O2 overcomes this spin restriction and allows microbicidal combustion. High exergonicity dioxygenation reactions yield electronically excited carbonyl products that relax by photon emission, i.e., phagocyte luminescence. Addition of high quantum yield substrates susceptible to spin allowed dioxygenation, i.e., chemiluminigenic substrates, greatly increases detection sensitivity and defines the nature of the oxygenating agent. Measurement of luminescence allows high sensitivity, real-time, and substrate-specific differential analysis of phagocyte dioxygenating activities. Under assay conditions where immune mediator and opsonin exposure are controlled, luminescence analysis of the initial phase of opsonin-stimulated oxygenation activity allows functional assessment of the opsonin receptor expression per circulating phagocyte and can be used to gauge the in vivo state of immune activation.
Topics: Animals; Antibiosis; Humans; Models, Biological; Oxidation-Reduction; Oxygen; Phagocytes; Receptors, Immunologic
PubMed: 7705297
DOI: 10.1289/ehp.94102s10201 -
Biochemistry. Biokhimiia Mar 2018Studies of the role of macrophages in phagocytosis are of great theoretical and practical importance for understanding how these cells are involved in the organism's...
Studies of the role of macrophages in phagocytosis are of great theoretical and practical importance for understanding how these cells are involved in the organism's defense response and in the development of various pathologies. Here we investigated phagocytic plasticity of THP-1 (acute monocytic human leukemia) cells at different stages (days 1, 3, and 7) of phorbol ester (PMA)-induced macrophage differentiation. Analysis of cytokine profiles showed that PMA at a concentration of 100 nM induced development of the proinflammatory macrophage population. The functional activity of macrophages was assessed on days 3 and 7 of differentiation using unlabeled latex beads and latex beads conjugated with ligands (gelatin, mannan, and IgG Fc fragment) that bind to the corresponding specific receptors. The general phagocytic activity increased significantly (1.5-2.0-fold) in the course of differentiation; phagocytosis occurred mostly through the Fc receptors, as shown previously for M1 macrophages. On day 7, the levels of phagocytosis of gelatin- and Fc-covered beads were high; however, the intensity of ingestion of mannan-conjugated beads via mannose receptors increased 2.5-3.0-fold as well, which indicated formation of cells with an alternative phenotype similar to that of M2 macrophages. Thus, the type and the plasticity of phagocytic activity at certain stages of macrophage differentiation can be associated with the formation of functionally mature morphological phenotype. This allows macrophages to exhibit their phagocytic potential in response to specific ligands. These data are of fundamental importance and can be used to develop therapeutic methods for correcting the M1/M2 macrophage ratio in an organism.
Topics: Cell Differentiation; Humans; Ligands; Macrophages; Phagocytes; Phagocytosis; Phenotype; THP-1 Cells; Tumor Cells, Cultured
PubMed: 29625541
DOI: 10.1134/S0006297918030021 -
Clinical and Experimental Immunology Jul 1996Since Aschoff's reticuloendothelial system was abandoned a few decades ago, classification and characterization of the mononuclear phagocyte and dendritic cell systems... (Comparative Study)
Comparative Study Review
Since Aschoff's reticuloendothelial system was abandoned a few decades ago, classification and characterization of the mononuclear phagocyte and dendritic cell systems have evolved separately or even in competition with one another. New information has now become available indicating that monocytes/macrophages and dendritic cells have a common origin in the bone marrow, and may even transdifferentiate. Morphological and functional distinctions-although valid under certain conditions-have been blurred by revelation of the versatility of monocytes/macrophages and dendritic cells in response to different contextual needs in inflammation and immunity. Monocytes/macrophages and dendritic cells share a sentinel, receptor/effector, and presentation mode, and may either activate or silence specific immune reactions. In keeping with the view of monocytes/macrophages and dendritic cells as interactive sentinels, we suggest that the mono-nuclear phagocyte and dendritic cell systems be replaced by the custocyte system (custos, Lat = sentinel, guard) as a unifying concept. Within the custocyte system, we recognize type I, type II, and type III custocytes. Type I and II custocytes exhibit predominance of presentation or effector/presenter interdependency, respectively, while type III custocytes are bipolar, passing through type I- and type II-like phases during their development and in inflammatory responses. The custocyte system brings into view monocytes/macrophages and dendritic cells as dynamic players in immunity and inflammation with a high degree of derivational, phenotypic, functional, and molecular plasticity.
Topics: Animals; Cell Differentiation; Dendritic Cells; Humans; Phagocytes
PubMed: 8697614
DOI: 10.1046/j.1365-2249.1996.d01-740.x -
Immunopharmacology and Immunotoxicology Aug 1995Protozoan parasites of the Leishmania genus are the causative agents of important diseases in humans and animals. During their life cycle in vertebrate hosts, protozoa... (Review)
Review
Protozoan parasites of the Leishmania genus are the causative agents of important diseases in humans and animals. During their life cycle in vertebrate hosts, protozoa are able to live and proliferate within phagolysosomes of host phagocytic cells. The capacity to live in this hostile environment is likely due to the cell surface glycoconjugate expression. In particular, lipophosphoglycan (LPG), a major surface glycoconjugate of Leishmania promastigotes, has been reported to play an active role in protecting parasites within phagolysosomes via the impairment of killing mechanisms. In this review, the authors emphasize some novel LPG-mediated escape mechanisms of promastigotes from human phagocyte responses, such as the impairment of oxidative burst and of chemotactic activity. In the light of these findings, the knowledge of biological actions of LPG may be useful in order to prepare a vaccine against human leishmaniasis, using LPG defective avirulent mutant strains.
Topics: Animals; Chemotaxis, Leukocyte; Dogs; Glycosphingolipids; Humans; Leishmania; Leishmaniasis; Phagocytes; Respiratory Burst
PubMed: 8576549
DOI: 10.3109/08923979509016390 -
Antioxidants & Redox Signaling 2006Phagocytic leukocytes generate reactive oxygen species important for the killing of invading microorganisms. The source of these oxidants is the NADPH oxidase, a tightly... (Review)
Review
Phagocytic leukocytes generate reactive oxygen species important for the killing of invading microorganisms. The source of these oxidants is the NADPH oxidase, a tightly controlled multicomponent enzyme made up of a membrane-associated catalytic moiety and cytosolic regulatory components that must assemble to form the active oxidase. The phagocyte NADPH oxidase was the first mammalian system shown to be directly regulated by a Rac GTPase. We review here our understanding of NADPH oxidase regulation by Rac, as well as the regulation of Rac itself, in phagocytic leukocytes. Rather than viewing Rac as a "cog" in the NADPH oxidase machinery, we argue for a view of Rac GTPases as critical "molecular switches" regulating the formation of ROS by phagocytic leukocytes under physiologic and pathologic conditions.
Topics: Animals; Cytochromes b; Humans; Models, Biological; NADPH Oxidases; Neutrophils; Phagocytes; Reactive Oxygen Species; cdc42 GTP-Binding Protein; rac GTP-Binding Proteins
PubMed: 16987009
DOI: 10.1089/ars.2006.8.1533 -
Journal of Leukocyte Biology Jul 1994Lipopolysaccharide (LPS), which is derived from the cell wall of gram-negative and some gram-positive bacteria, plays a major role is the pathogenesis of septic shock.... (Review)
Review
Lipopolysaccharide (LPS), which is derived from the cell wall of gram-negative and some gram-positive bacteria, plays a major role is the pathogenesis of septic shock. Initiation of these responses depends on LPS interaction with a number of immune cells, not least the mononuclear phagocyte (MP). Mononuclear phagocytes bind the LPS/lipopolysaccharide-binding protein complex through the CD14 receptor and thus mediate the release of a wide range of inflammatory mediators. Release of these mediators is teleologically beneficial but under certain circumstances may be detrimental, resulting in the systemic inflammatory response syndrome. The development of this syndrome is not clearly understood but appears, in part, to be dependent on the ability of the host to respond to these mediators. This review evaluates the mechanisms of LPS-MP interaction and the therapeutic strategies aimed at inhibiting this interaction.
Topics: Animals; Endotoxins; Humans; Inflammation; Lipopolysaccharides; Phagocytes
PubMed: 8027674
DOI: 10.1002/jlb.56.1.95 -
Advances in Nephrology From the Necker... 2001
Review
Topics: Animals; Apoptosis; Glomerulonephritis; Humans; Phagocytes
PubMed: 11692460
DOI: No ID Found -
Immunobiology Apr 1982
Review
Topics: Animals; Bone Marrow Cells; Cell Differentiation; Cell Division; Cell Movement; Connective Tissue Cells; Exudates and Transudates; Humans; Inflammation; Lymph Nodes; Lymphoid Tissue; Macrophage Activation; Macrophages; Mice; Monocytes; Phagocytes; Pulmonary Alveoli; Rats; Terminology as Topic; Thymus Gland
PubMed: 7047368
DOI: 10.1016/S0171-2985(82)80072-7 -
Developmental and Comparative Immunology 1983The plasmatocytes and granular cells are the most important hemocyte types involved in the cellular reactions of insects. These two hemocytes are obviously characterized... (Review)
Review
The plasmatocytes and granular cells are the most important hemocyte types involved in the cellular reactions of insects. These two hemocytes are obviously characterized with the adhesive morphology. Particularly, the granular cells in Bombyx mori have many long filopodia, and they are considered to play roles in catching the foreign materials invading into the hemocoel and also in obtaining some phagocytic signals during elongation process. The second part of this mini-review is a continuation of the previous summary (1) in which the immunocompetent cells in B.mori were described. Here, possible role of hemolymph factor is presented with much attention to the filopodial function of phagocytic granular cells of B.mori.
Topics: Agglutinins; Animals; Bombyx; Cell Adhesion; Hemolymph; Immunity, Cellular; Phagocytes
PubMed: 6347738
DOI: 10.1016/0145-305x(83)90001-0 -
General and Comparative Endocrinology May 2011Coping with physical, chemical and biological disturbances depends on an extensive repertoire of physiological, endocrinological and immunological responses. Fish... (Review)
Review
Coping with physical, chemical and biological disturbances depends on an extensive repertoire of physiological, endocrinological and immunological responses. Fish provide intriguing models to study bi-directional interaction between the neuroendocrine and the immune systems. Macrophages and granulocytes are the main actors in the first and rapid innate immune response. They are resident in different organs and are moreover rapidly recruited and activated upon infection. They act in response to recognition of pathogen-associated molecular patterns (PAMPs) via a repertoire of surface and intracellular receptors by inducing a plethora of defense reactions aiming to eradicate the pathogen. Subsequent production of inflammatory mediators stimulates other leukocytes required to develop an adaptive and specific antibody response. The type of phagocyte reaction will therefore depend on their differentiation state, specific receptor repertoire and their specific location. Apart from these pathogen induced responses, immune reactivity may be modulated by neuroendocrine factors. Over the last years we extensively studied changes in carp stress axis activity and the effect of its end-products on the immune system in an acute stress paradigm. We focus on specific neuroendocrine receptors on leukocytes and their effect on crucial phagocyte activities. We performed identification and functional analyses of different glucocorticoid, opioid and adrenergic receptors on carp phagocytes. Results show that their ligands of neuroendocrine origin may have substantial impact on specific phagocyte functions in a differential way. Inflammatory and microbicidal responses fight pathogens but may be detrimental to the host tissue. Neuroendocrine modulation may regulate inflammation to reach an optimum defense while preventing excessive host cell damage.
Topics: Animals; Cell Polarity; Fishes; Immunity, Innate; Models, Biological; Neuroimmunomodulation; Neurosecretory Systems; Neurotransmitter Agents; Phagocytes; Phagocytosis
PubMed: 21262228
DOI: 10.1016/j.ygcen.2011.01.004