Surfactant protein A binds to IgG and enhances phagocytosis of IgG-opsonized erythrocytes

Lin, Peggy M.; Wright, Jo Rae

doi:10.1152/ajplung.00188.2006

Cited by 15 publications

(11 citation statements)

References 21 publications

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“…42,45 Surfactant protein A also interacts with IgG and complement proteins such as C1q. 46,47 Interestingly, C1q and natural IgM can directly recognize molecular patterns present on certain cells under specific biological situations; for example, they recognize damage-or danger-associated molecular patterns (DAMPs) of dying cells. [48][49][50] Therefore, collectins may further regulate or utilize the complement system for effective immune surveillance and regulation of tissue inflammation.…”

Section: Clearance Of Dying Cellsmentioning

confidence: 99%

Antibody equivalent molecules of the innate immune system: parallels between innate and adaptive immune proteins

Palaniyar

2010

Innate Immun

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Soluble pattern-recognition innate immune proteins functionally resemble the antibodies of the adaptive immune system. Two major families of such proteins are ficolins and collectins or collagenous lectins (e.g. mannose-binding lectin [MBL], surfactant proteins [SP-A and SP-D] and conglutinin). In general, subunits of ficolins and collectins recognize the carbohydrate arrays of their targets via globular trimeric carbohydrate-recognition domains (CRDs) whereas IgG, IgM and other antibody isotypes recognize proteins via dimeric antigen-binding domains (Fab). Considering the structure and functions of these proteins, ficolins and MBL are analogous to molecules with the complement activating functions of C1q and the target recognition ability of IgG. Although the structure of SP-A is similar to MBL, it does not activate the complement system. Surfactant protein-D and conglutinin could be considered as the collagenous non-complement activating giant IgMs of the innate immune system. Proteins such as peptidoglycan-recognition proteins, pentraxins and agglutinin gp-340/DMBT1 are also pattern-recognition proteins. These proteins may be considered as different isotypes of antibody-like molecules. Proteins such as defensins, cathelicidins and lactoferrins directly or indirectly alter microbes or microbial growth. These proteins may not be considered as antibodies of the innate immune system. Hence, ficolins and collectins could be considered as specialized 'antibodies of the innate immune system' instead of 'ante-antibody' innate immune molecules. The discovery, structure, functions and future research directions of many of these soluble proteins and receptors such as Toll-like and NOD-like receptors are discussed in this special issue of Innate Immunity.

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Section: Clearance Of Dying Cellsmentioning

confidence: 99%

Antibody equivalent molecules of the innate immune system: parallels between innate and adaptive immune proteins

Palaniyar

2010

Innate Immun

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“…This may occur via opsonization of the beads and/or aggregation of beads. SP-A is known to aggregate various bacteria (12,28) and has been reported to bind to immunoglobulins (13,16). We found that SP-A increased aggregation of IgG-coated but not BSA-coated beads and that SP-A bound to both kinds of beads, but much more to IgG-coated beads.…”

Section: Discussionmentioning

confidence: 63%

“…Since we had previously demonstrated that SP-A synergistically enhanced IgG-mediated phagocytosis in macrophages (16,22), we hypothesized that SP-A may have similar synergistic effects on IgG-mediated phagocytosis in inflammatory neutrophils. To address this question, polystyrene beads were covalently coated with BSA and treated with anti-BSA IgG, thereby presenting a target similar to an IgG-opsonized pathogen.…”

mentioning

confidence: 99%

Surfactant protein A regulates IgG-mediated phagocytosis in inflammatory neutrophils

Wofford¹,

Wright²

2007

American Journal of Physiology-Lung Cellular and Molecular Phys

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Surfactant proteins (SP)-A and SP-D have been shown to affect the functions of a variety of innate immune cells and to interact with various immune proteins such as complement and immunoglobulins. The goal of the current study is to test the hypothesis that SP-A regulates IgG-mediated phagocytosis by neutrophils, which are major effector cells of the innate immune response that remove invading pathogens by phagocytosis and by extracellular killing mediated by reactive oxygen and nitrogen. We have previously shown that SP-A stimulates chemotaxis by inflammatory, but not peripheral, neutrophils. To evaluate the ability of SP-A to modulate IgG-mediated phagocytosis, polystyrene beads were coated with BSA and treated with anti-BSA IgG. SP-A significantly and specifically enhanced IgG-mediated phagocytosis by inflammatory neutrophils, but it had no effect on beads not treated with IgG. SP-A bound to IgG-coated beads and enhanced their uptake via direct interactions with the beads as well as direct interactions with the neutrophils. SP-A did not affect reactive oxygen production or binding of IgG to neutrophils and had modest effects on polymerization of actin. These data suggest that SP-A plays an important role in mediating the phagocytic response of neutrophils to IgG-opsonized particles.

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“…Lung surfactant, and specifically also its main protein component surfactant protein A (SP-A), has, for instance, been known to enhance phagocytosis of bacteria by AM (52,57). A recent study revealed that SP-A enhances uptake of IgG-coated erythrocytes, suggesting that SP-A might be influencing Fc receptor-mediated uptake (50).…”

Section: Discussionmentioning

confidence: 99%

Impact of the FcγII-receptor on quartz uptake and inflammatory response by alveolar macrophages

Haberzettl¹,

Schins²,

Höhr³

et al. 2008

American Journal of Physiology-Lung Cellular and Molecular Phys

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The inflammatory response following particle inhalation is described as a key event in the development of lung diseases, e.g., fibrosis and cancer. The essential role of alveolar macrophages (AM) in the pathogenicity of particles through their functions in lung clearance and mediation of inflammation is well known. However, the molecular mechanisms and direct consequences of particle uptake are still unclear. Inhibition of different classic phagocytosis receptors by flow cytometry shows a reduction of the dose-dependent quartz particle (DQ12) uptake in the rat AM cell line NR8383. Thereby the strongest inhibitory effect was observed by blocking the FcgammaII-receptor (FcgammaII-R). Fluorescence immunocytochemistry, demonstrating FcgammaII-R clustering at particle binding sites as well as transmission electron microscopy, visualizing zippering mechanism-like morphological changes, confirmed the role of the FcgammaII-R in DQ12 phagocytosis. FcgammaII-R participation in DQ12 uptake was further strengthened by the quartz-induced activation of the Src-kinase Lyn, the phospho-tyrosine kinases Syk (spleen tyrosine kinase) and PI3K (phosphatidylinositol 3-kinase), as shown by Western blotting. Activation of the small GTPases Rac1 and Cdc42, shown by immunoprecipitation, as well as inhibition of tyrosine kinases, GTPases, or Rac1 provided further support for the role of the FcgammaII-R. Consistent with the uptake results, FcgammaII-R activation with its specific ligand caused a similar generation of reactive oxygen species and TNF-alpha release as observed after treatment with DQ12. In conclusion, our results indicate a major role of FcgammaII-R and its downstream signaling cascade in the phagocytosis of quartz particles in AM as well as in the associated generation and release of inflammatory mediators.

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Surfactant protein A binds to IgG and enhances phagocytosis of IgG-opsonized erythrocytes

Abstract: Lin, Peggy M., and Jo Rae Wright. Surfactant protein A binds to IgG and enhances phagocytosis of IgG-opsonized erythrocytes.

Cited by 15 publications

References 21 publications

Antibody equivalent molecules of the innate immune system: parallels between innate and adaptive immune proteins

Antibody equivalent molecules of the innate immune system: parallels between innate and adaptive immune proteins

Surfactant protein A regulates IgG-mediated phagocytosis in inflammatory neutrophils

Impact of the FcγII-receptor on quartz uptake and inflammatory response by alveolar macrophages

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