Fibrinogen binds IgG antibody and enhances IgG-mediated phagocytosis1

Boehm, Tobias K; DeNardin, Ernesto

doi:10.3233/hab-2008-173-401

Cited by 17 publications

(14 citation statements)

References 37 publications

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“…This binding is also specific to IgG, as it occurs much less with IgM[14] and does not occur with BSA or GFP (data not shown). Since binding occurred under physiologic concentrations of fibrinogen, we sought to determine if binding is dependent on phase and surface concentration in an effort to find optimal binding conditions and hints of physiologic function.…”

Section: Resultsmentioning

confidence: 99%

“…It is possible that this might be due to avidity effects, as a high surface density of IgG might allow for binding of one fibrinogen molecule to several IgG molecules, thus leading to increased binding strength. We have previously demonstrated the potential for multiple binding sites (Fab, Fc portions)[14], which would make fibrinogen binding to IgG analogous to IgG antibody binding to antigens. Physiologically, it appears that fibrinogen binding to IgG preferentially occurs on surfaces coated with a high density of IgG, which occurs on successfully opsonized bacteria.…”

Section: Discussionmentioning

confidence: 99%

“…We recently demonstrated specific, saturable fibrinogen binding to IgG and IgA antibodies, but not IgM antibodies. Binding seems to occur predominantly on the IgG heavy chains, as specific, saturable binding demonstrable is present on Fab and Fc fragments, but strongest for Fc fragments and heavy chains [14]. …”

Section: Introductionmentioning

confidence: 99%

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Concentration-dependent effect of fibrinogen on IgG-specific antigen binding and phagocytosis

Boehm

Sojar

DeNardin

2010

Cellular Immunology

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In this paper, we aim to characterize fibrinogen-IgG interactions, and explore how fibrinogen alters IgG-mediated phagocytosis.Using enzyme-linked binding assays, we found that fibrinogen binding to IgG is optimized for surfaces coated with high levels of IgG. Using a similar method, we have shown that for an antigen unable to specifically bind fibrinogen, fibrinogen enhances binding of antibodies towards that antigen. For binding of IgG antibodies to cells expressing Fc receptors, we found a bimodal binding response, where low levels of fibrinogen enhance binding of antibody to Fc receptors and high levels reduce it. This corresponds to a bimodal effect on phagocytosis of IgG-coated particles, which is inhibited in the presence of excess IgG during coating of the particles with antibodies and fibrinogen.We conclude that fibrinogen can modulate phagocytosis of IgG-coated particles in vitro by changing IgG binding behavior, and that high fibrinogen levels could negatively affect phagocytosis.

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Section: Resultsmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

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Concentration-dependent effect of fibrinogen on IgG-specific antigen binding and phagocytosis

Boehm

Sojar

DeNardin

2010

Cellular Immunology

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“…S5) including native- or modified-self molecules, as well as non-self (i.e. microbial pathogen) components (Boehm and DeNardin, 2008; Yakubenko et al, 2002). Thus, we envisage Fcγ receptors as conferring specificity to the phagocytic event, while the more promiscuous integrins increase the avidity and efficiency of the process.…”

Section: Discussionmentioning

confidence: 99%

Integrins Form an Expanding Diffusional Barrier that Coordinates Phagocytosis

Freeman

Goyette

Furuya

et al. 2016

Cell

178

202

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Summary Phagocytosis is initiated by lateral clustering of receptors, which in turn activates Src-family kinases (SFKs). Activation of SFKs requires depletion of tyrosine phosphatases from the area of particle engagement. We investigated how the major phosphatase CD45 is excluded from contact sites, using single-molecule tracking. The mobility of CD45 increased markedly upon engagement of Fcγ receptors. While individual CD45 molecules moved randomly, they were displaced from the advancing phagocytic cup by an expanding diffusional barrier. By micropatterning IgG, the ligand of Fcγ receptors, we found that the barrier extended well beyond the perimeter of the receptor-ligand engagement zone. Second messengers generated by Fcγ receptors activated integrins, which formed an actin-tethered diffusion barrier that excluded CD45. The expanding integrin wave facilitates the “zippering” of Fcγ receptors onto the target and integrates the information from sparse receptor-ligand complexes, coordinating the progression and ultimate closure of the phagocytic cup.

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“…Our results also indicate that fibrinogen may bind anti‐IgG and, most likely, this reaction is specific. In the studies with immobilized IgG, it has been evidenced that fibrinogen binds to several sites within the Fc and Fab portions, and thus, it may augment the function of IgG during phagocytosis [20].…”

Section: Discussionmentioning

confidence: 99%

Modified C‐Reactive Protein Selectively Binds to Immunoglobulins

et al. 2012

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Modified C‐reactive protein (mCRP) has been reported to non‐specifically bind to immunoglobulins; notwithstanding, the nature of these interactions is not clear. The aim of this study was to investigate the binding of antibodies directed against HSA and IgG to mCRP, fibrinogen (Fg), IgG, fibronectin (Fn) and C1q and its contaminants. We also studied the binding of mCRP to the antibodies directed towards receptors involved in CRP signalling (anti‐CD32, anti‐CD16). For the analysis of such interactions, a combination of ELISA and Western immunoblotting has been applied. The tested antibodies powerfully bound to either the contaminations of purified proteins (Fg, IgG, Fn and mCRP) or interacted directly with some of these proteins (C1q, mCRP, Fg). The effectiveness of anti‐HSA binding to immobilized proteins was influenced by the antigenic specificity of the antibody, the content of various protein fractions in the contaminants of a given protein (albumin augmented the interactions), overall protein purity and a natural avidity of a given protein towards immunoglobulins. The relative binding of anti‐HSA or anti‐IgG to immobilized mCRP was considerably lower than that observed for plasma proteins. Furthermore, the strength of the direct interaction between immunoglobulins and mCRP varied from the lack of response (anti‐HSA) or a negligible response (anti‐IgG) to the relatively high signal (human IgG, anti‐CD16, anti‐CD32), as compared to the control. Based on these observations, we conclude that the binding of mCRP to immunoglobulins cannot be easily generalized as a kind of some universal phenomenon.

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Fibrinogen binds IgG antibody and enhances IgG-mediated phagocytosis1

Cited by 17 publications

References 37 publications

Concentration-dependent effect of fibrinogen on IgG-specific antigen binding and phagocytosis

Concentration-dependent effect of fibrinogen on IgG-specific antigen binding and phagocytosis

Integrins Form an Expanding Diffusional Barrier that Coordinates Phagocytosis

Modified C‐Reactive Protein Selectively Binds to Immunoglobulins

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