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Fc Receptors

A special issue of International Journal of Molecular Sciences (ISSN 1422-0067). This special issue belongs to the section "Molecular Immunology".

Deadline for manuscript submissions: closed (31 August 2021) | Viewed by 53539

Special Issue Editor

Dr. Markus Biburger

E-Mail Website
Guest Editor
1. Division of Genetics, Department of Biology, University of Erlangen-Nürnberg, Erlangen, Germany
2. Medical Immunology Campus Erlangen, University of Erlangen-Nürnberg, Erlangen, Germany
Interests: antibody effector functions; myeloid effector cells; immunological tumor targeting; novel CAR immunotherapy strategies; imaging
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

Antibodies are central mediators of immunological defense mechanisms, are used as therapeutic agents in the clinics, but are also functionally involved in various immune-mediated disorders. Whereas antibodies accomplish some of their biological functions autonomously, many effector functions strictly depend on the interaction with distinct receptors (FcR) that bind antibody Fc domains. The purpose of this Special Issue on “Fc Receptors” is to report the recent progress achieved in the exceedingly complex topic of the interaction between these receptors and their antibody ligands.

Due to the multitude of:

  • Molecular partners that can be involved in antibody–Fc receptor interactions;
  • Patterns of glycosylation which affect binding affinities;
  • Biological functions, such as IgG homeostasis and transcytosis by FcRn, proteasomal degradation of intracellular antibody load via cytosolic TRIM21, killing or phagocytosis of opsonized target cells via Fcγ receptors, activation of the immune system e.g. by histamine release upon FcεR triggering on mast cells, and much more;
  • Members of the rather novel family of FcR-like (FCRL) molecules;
  • Clinical manifestations of adverse FcR engagement such as type I and some type II hypersensitivity reactions and autoimmune diseases;
  • Clinical applications of FcR-mediated antibody effector functions, e.g., in cancer immunotherapy;
  • The various effector cell types involved in these processes;
  • Genetic polymorphisms in human FcRs, which are associated with susceptibility to various diseases and/or differences in the effectiveness of therapeutic antibodies;

there is a correspondingly broad field of topics that will fit into this Special Issue. In addition to biological, preclinical, and clinical research, also work that focusses on mathematical and structural models is welcome to be submitted.

This Special Issue on “Fc Receptors” invites original research and—since the International Journal of Molecular Sciences may additionally reach an audience beyond that of common Immunology journals—also review articles in the field. 

Dr. Markus Biburger
Guest Editor

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. International Journal of Molecular Sciences is an international peer-reviewed open access semimonthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. There is an Article Processing Charge (APC) for publication in this open access journal. For details about the APC please see here. Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • FcγR
  • FcεR
  • FcμR
  • FcαR
  • FcRn
  • neonatal Fc receptor
  • TRIM21
  • cytosolic Fc receptor
  • antibody effector functions
  • Fc–Fc receptor interaction
  • immune regulation
  • inflammation
  • immunotherapy
  • antibody-dependent cellular cytotoxicity
  • antibody-dependent cellular phagocytosis
  • mast cells
  • neutrophils
  • macrophages
  • monocytes
  • natural killer cells

Published Papers (12 papers)

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Editorial

Jump to: Research, Review

4 pages, 192 KiB  
Editorial
My Name Is Legion, for We Are Many—The Complex Community of Antibody Receptors
by Markus Biburger
Int. J. Mol. Sci. 2023, 24(20), 15226; https://doi.org/10.3390/ijms242015226 - 16 Oct 2023
Viewed by 601
Abstract
Antibodies act as the central mediators of immunological defense mechanisms, therapeutic agents within clinics, and the mediators of various immune-mediated disorders [...] Full article
(This article belongs to the Special Issue Fc Receptors)

Research

Jump to: Editorial, Review

22 pages, 11380 KiB  
Article
There Is Strength in Numbers: Quantitation of Fc Gamma Receptors on Murine Tissue-Resident Macrophages
by Christof Vorsatz, Niklas Friedrich, Falk Nimmerjahn and Markus Biburger
Int. J. Mol. Sci. 2021, 22(22), 12172; https://doi.org/10.3390/ijms222212172 - 10 Nov 2021
Cited by 4 | Viewed by 3252
Abstract
Many of the effector functions of antibodies rely on the binding of antibodies/immune complexes to cellular Fcγ receptors (FcγRs). Since the majority of innate immune effector cells express both activating and inhibitory Fc receptors, the outcome of the binding of immune complexes to [...] Read more.
Many of the effector functions of antibodies rely on the binding of antibodies/immune complexes to cellular Fcγ receptors (FcγRs). Since the majority of innate immune effector cells express both activating and inhibitory Fc receptors, the outcome of the binding of immune complexes to cells of a given population is influenced by the relative affinities of the respective IgG subclasses to these receptors, as well as by the numbers of activating and inhibitory FcγRs on the cell surface. A group of immune cells that has come into focus more recently is the various subsets of tissue-resident macrophages. The central functions of FcγRs on tissue macrophages include the clearance of opsonized pathogens, the removal of small immune complexes from the circulation and the depletion of antibody-opsonized cells in the therapy of autoimmunity and cancer. Despite these essential functions of FcγRs on tissue-resident macrophages, an in-depth quantification of FcγRs is lacking. Thus, the aim of our current study was to quantify the various Fcγ receptors on macrophages in murine liver, lung, kidney, brain, skin and spleen. Our study identified a pronounced heterogeneity between FcγR expression patterns of the different tissue macrophages, which may reflect their specialized functions within their unique niches in different organ environments. Full article
(This article belongs to the Special Issue Fc Receptors)
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10 pages, 1360 KiB  
Article
Involvement of Virus-Induced Interferon Production in IgG Autoantibody-Mediated Anemia
by Sarah Legrain, Dan Su, Mélanie Gaignage, Cor Breukel, Jill Claassens, Conny Brouwers, Margot M. Linssen, Shozo Izui, J. Sjef Verbeek and Jean-Paul Coutelier
Int. J. Mol. Sci. 2021, 22(16), 9027; https://doi.org/10.3390/ijms22169027 - 21 Aug 2021
Cited by 1 | Viewed by 1567
Abstract
Infection with viruses, such as the lactate dehydrogenase-elevating virus (LDV), is known to trigger the onset of autoimmune anemia through the enhancement of the phagocytosis of autoantibody-opsonized erythrocytes by activated macrophages. Type I interferon receptor-deficient mice show enhanced anemia, which suggests a protective [...] Read more.
Infection with viruses, such as the lactate dehydrogenase-elevating virus (LDV), is known to trigger the onset of autoimmune anemia through the enhancement of the phagocytosis of autoantibody-opsonized erythrocytes by activated macrophages. Type I interferon receptor-deficient mice show enhanced anemia, which suggests a protective effect of these cytokines, partly through the control of type II interferon production. The development of anemia requires the expression of Fcγ receptors (FcγR) I, III, and IV. Whereas LDV infection decreases FcγR III expression, it enhances FcγR I and IV expression in wild-type animals. The LDV-associated increase in the expression of FcγR I and IV is largely reduced in type I interferon receptor-deficient mice, through both type II interferon-dependent and -independent mechanisms. Thus, the regulation of the expression of FcγR I and IV, but not III, by interferons may partly explain the exacerbating effect of LDV infection on anemia that results from the enhanced phagocytosis of IgG autoantibody-opsonized erythrocytes. Full article
(This article belongs to the Special Issue Fc Receptors)
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12 pages, 19844 KiB  
Article
Differences between Human and Mouse IgM Fc Receptor (FcµR)
by Hiromi Kubagawa, Christopher M. Skopnik, Khlowd Al-Qaisi, Rosaleen A. Calvert, Kazuhito Honjo, Yoshiki Kubagawa, Ruth Teuber, Pedram Mahmoudi Aliabadi, Philipp Enghard, Andreas Radbruch and Brian J. Sutton
Int. J. Mol. Sci. 2021, 22(13), 7024; https://doi.org/10.3390/ijms22137024 - 29 Jun 2021
Cited by 8 | Viewed by 2475
Abstract
Both non-immune “natural” and antigen-induced “immune” IgM are important for protection against pathogens and for regulation of immune responses to self-antigens. Since the bona fide IgM Fc receptor (FcµR) was identified in humans by a functional cloning strategy in 2009, the roles of [...] Read more.
Both non-immune “natural” and antigen-induced “immune” IgM are important for protection against pathogens and for regulation of immune responses to self-antigens. Since the bona fide IgM Fc receptor (FcµR) was identified in humans by a functional cloning strategy in 2009, the roles of FcµR in these IgM effector functions have begun to be explored. In this short essay, we describe the differences between human and mouse FcµRs in terms of their identification processes, cellular distributions and ligand binding activities with emphasis on our recent findings from the mutational analysis of human FcµR. We have identified at least three sites of human FcµR, i.e., Asn66 in the CDR2, Lys79 to Arg83 in the DE loop and Asn109 in the CDR3, responsible for its constitutive IgM-ligand binding. Results of computational structural modeling analysis are consistent with these mutational data and a model of the ligand binding, Ig-like domain of human FcµR is proposed. Serendipitously, substitution of Glu41 and Met42 in the CDR1 of human FcµR with mouse equivalents Gln and Leu, either single or more prominently in combination, enhances both the receptor expression and IgM binding. These findings would help in the future development of preventive and therapeutic interventions targeting FcµR. Full article
(This article belongs to the Special Issue Fc Receptors)
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11 pages, 1573 KiB  
Article
Association of IgG1 Antibody Clearance with FcγRIIA Polymorphism and Platelet Count in Infliximab-Treated Patients
by Gilles Thibault, Gilles Paintaud, Hsueh Cheng Sung, Laurie Lajoie, Edouard Louis, the GETAID, Celine Desvignes, Hervé Watier, Valérie Gouilleux-Gruart and David Ternant
Int. J. Mol. Sci. 2021, 22(11), 6051; https://doi.org/10.3390/ijms22116051 - 3 Jun 2021
Cited by 2 | Viewed by 2337
Abstract
The FcγRIIA/CD32A is mainly expressed on platelets, myeloid and several endothelial cells. Its affinity is considered insufficient for allowing significant binding of monomeric IgG, while its H131R polymorphism (histidine > arginine at position 131) influences affinity for multimeric IgG2. Platelet FcγRIIA has been [...] Read more.
The FcγRIIA/CD32A is mainly expressed on platelets, myeloid and several endothelial cells. Its affinity is considered insufficient for allowing significant binding of monomeric IgG, while its H131R polymorphism (histidine > arginine at position 131) influences affinity for multimeric IgG2. Platelet FcγRIIA has been reported to contribute to IgG-containing immune-complexe clearance. Given our finding that platelet FcγRIIA actually binds monomeric IgG, we investigated the role of platelets and FcγRIIA in IgG antibody elimination. We used pharmacokinetics analysis of infliximab (IgG1) in individuals with controlled Crohn’s disease. The influence of platelet count and FcγRIIA polymorphism was quantified by multivariate linear modelling. The infliximab half-life increased with R allele number (13.2, 14.4 and 15.6 days for HH, HR and RR patients, respectively). It decreased with increasing platelet count in R carriers: from ≈20 days (RR) and ≈17 days (HR) at 150 × 109/L, respectively, to ≈13 days (both HR and RR) at 350 × 109/L. Moreover, a flow cytometry assay showed that infliximab and monomeric IgG1 bound efficiently to platelet FcγRIIA H and R allotypes, whereas panitumumab and IgG2 bound poorly to the latter. We propose that infliximab (and presumably any IgG1 antibody) elimination is partly due to an unappreciated mechanism dependent on binding to platelet FcγRIIA, which is probably tuned by its affinity for IgG2. Full article
(This article belongs to the Special Issue Fc Receptors)
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Review

Jump to: Editorial, Research

15 pages, 1687 KiB  
Review
Regulation of Trafficking and Signaling of the High Affinity IgE Receptor by FcεRIβ and the Potential Impact of FcεRIβ Splicing in Allergic Inflammation
by Greer K. Arthur and Glenn Cruse
Int. J. Mol. Sci. 2022, 23(2), 788; https://doi.org/10.3390/ijms23020788 - 12 Jan 2022
Cited by 6 | Viewed by 3321
Abstract
Mast cells are tissue-resident immune cells that function in both innate and adaptive immunity through the release of both preformed granule-stored mediators, and newly generated proinflammatory mediators that contribute to the generation of both the early and late phases of the allergic inflammatory [...] Read more.
Mast cells are tissue-resident immune cells that function in both innate and adaptive immunity through the release of both preformed granule-stored mediators, and newly generated proinflammatory mediators that contribute to the generation of both the early and late phases of the allergic inflammatory response. Although mast cells can be activated by a vast array of mediators to contribute to homeostasis and pathophysiology in diverse settings and contexts, in this review, we will focus on the canonical setting of IgE-mediated activation and allergic inflammation. IgE-dependent activation of mast cells occurs through the high affinity IgE receptor, FcεRI, which is a multimeric receptor complex that, once crosslinked by antigen, triggers a cascade of signaling to generate a robust response in mast cells. Here, we discuss FcεRI structure and function, and describe established and emerging roles of the β subunit of FcεRI (FcεRIβ) in regulating mast cell function and FcεRI trafficking and signaling. We discuss current approaches to target IgE and FcεRI signaling and emerging approaches that could target FcεRIβ specifically. We examine how alternative splicing of FcεRIβ alters protein function and how manipulation of splicing could be employed as a therapeutic approach. Targeting FcεRI directly and/or IgE binding to FcεRI are promising approaches to therapeutics for allergic inflammation. The characteristic role of FcεRIβ in both trafficking and signaling of the FcεRI receptor complex, the specificity to IgE-mediated activation pathways, and the preferential expression in mast cells and basophils, makes FcεRIβ an excellent, but challenging, candidate for therapeutic strategies in allergy and asthma, if targeting can be realized. Full article
(This article belongs to the Special Issue Fc Receptors)
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26 pages, 2242 KiB  
Review
The Role of Fc Receptors on the Effectiveness of Therapeutic Monoclonal Antibodies
by Patricia Gogesch, Simone Dudek, Ger van Zandbergen, Zoe Waibler and Martina Anzaghe
Int. J. Mol. Sci. 2021, 22(16), 8947; https://doi.org/10.3390/ijms22168947 - 19 Aug 2021
Cited by 40 | Viewed by 9690
Abstract
Since the approval of the first monoclonal antibody (mAb) in 1986, a huge effort has been made to guarantee safety and efficacy of therapeutic mAbs. As of July 2021, 118 mAbs are approved for the European market for a broad range of clinical [...] Read more.
Since the approval of the first monoclonal antibody (mAb) in 1986, a huge effort has been made to guarantee safety and efficacy of therapeutic mAbs. As of July 2021, 118 mAbs are approved for the European market for a broad range of clinical indications. In order to ensure clinical efficacy and safety aspects, (pre-)clinical experimental approaches evaluate the respective modes of action (MoA). In addition to antigen-specificity including binding affinity and -avidity, MoA comprise Fc-mediated effector functions such as antibody dependent cellular cytotoxicity (ADCC) and the closely related antibody dependent cellular phagocytosis (ADCP). For this reason, a variety of cell-based assays have been established investigating effector functions of therapeutic mAbs with different effector/target-cell combinations and several readouts including Fcγ receptor (FcγR)-mediated lysis, fluorescence, or luminescence. Optimized FcγR-mediated effector functions regarding clinical safety and efficacy are addressed with modification strategies such as point mutations, altered glycosylation patterns, combination of different Fc subclasses (cross isotypes), and Fc-truncation of the mAb. These strategies opened the field for a next generation of therapeutic mAbs. In conclusion, it is of major importance to consider FcγR-mediated effector functions for the efficacy of therapeutic mAbs. Full article
(This article belongs to the Special Issue Fc Receptors)
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Graphical abstract

27 pages, 2905 KiB  
Review
On the Use of Surface Plasmon Resonance Biosensing to Understand IgG-FcγR Interactions
by Catherine Forest-Nault, Jimmy Gaudreault, Olivier Henry, Yves Durocher and Gregory De Crescenzo
Int. J. Mol. Sci. 2021, 22(12), 6616; https://doi.org/10.3390/ijms22126616 - 21 Jun 2021
Cited by 23 | Viewed by 3927
Abstract
Surface plasmon resonance (SPR)-based optical biosensors offer real-time and label-free analysis of protein interactions, which has extensively contributed to the discovery and development of therapeutic monoclonal antibodies (mAbs). As the biopharmaceutical market for these biologics and their biosimilars is rapidly growing, the role [...] Read more.
Surface plasmon resonance (SPR)-based optical biosensors offer real-time and label-free analysis of protein interactions, which has extensively contributed to the discovery and development of therapeutic monoclonal antibodies (mAbs). As the biopharmaceutical market for these biologics and their biosimilars is rapidly growing, the role of SPR biosensors in drug discovery and quality assessment is becoming increasingly prominent. One of the critical quality attributes of mAbs is the N-glycosylation of their Fc region. Other than providing stability to the antibody, the Fc N-glycosylation influences immunoglobulin G (IgG) interactions with the Fcγ receptors (FcγRs), modulating the immune response. Over the past two decades, several studies have relied on SPR-based assays to characterize the influence of N-glycosylation upon the IgG-FcγR interactions. While these studies have unveiled key information, many conclusions are still debated in the literature. These discrepancies can be, in part, attributed to the design of the reported SPR-based assays as well as the methodology applied to SPR data analysis. In fact, the SPR biosensor best practices have evolved over the years, and several biases have been pointed out in the development of experimental SPR protocols. In parallel, newly developed algorithms and data analysis methods now allow taking into consideration complex biomolecular kinetics. In this review, we detail the use of different SPR biosensing approaches for characterizing the IgG-FcγR interactions, highlighting their merit and inherent experimental complexity. Furthermore, we review the latest SPR-derived conclusions on the influence of the N-glycosylation upon the IgG-FcγR interactions and underline the differences and similarities across the literature. Finally, we explore new avenues taking advantage of novel computational analysis of SPR results as well as the latest strategies to control the glycoprofile of mAbs during production, which could lead to a better understanding and modelling of the IgG-FcγRs interactions. Full article
(This article belongs to the Special Issue Fc Receptors)
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20 pages, 784 KiB  
Review
FcRn as a Transporter for Nasal Delivery of Biologics: A Systematic Review
by Maxime Fieux, Sandra Le Quellec, Sophie Bartier, André Coste, Bruno Louis, Caroline Giroudon, Mikail Nourredine and Emilie Bequignon
Int. J. Mol. Sci. 2021, 22(12), 6475; https://doi.org/10.3390/ijms22126475 - 17 Jun 2021
Cited by 8 | Viewed by 3389
Abstract
FcRn plays a major role in regulating immune homeostasis, but it is also able to transport biologics across cellular barriers. The question of whether FcRn could be an efficient transporter of biologics across the nasal epithelial barrier is of particular interest, as it [...] Read more.
FcRn plays a major role in regulating immune homeostasis, but it is also able to transport biologics across cellular barriers. The question of whether FcRn could be an efficient transporter of biologics across the nasal epithelial barrier is of particular interest, as it would allow a less invasive strategy for the administration of biologics in comparison to subcutaneous, intramuscular or intravenous administrations, which are often used in clinical practice. A focused systematic review was conducted following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. It was registered on the international prospective register of systematic reviews PROSPERO, which helped in identifying articles that met the inclusion criteria. Clinical and preclinical studies involving FcRn and the nasal delivery of biologics were screened, and the risk of bias was assessed across studies using the Oral Health Assessment Tool (OHAT). Among the 12 studies finally included in this systematic review (out of the 758 studies screened), 11 demonstrated efficient transcytosis of biologics through the nasal epithelium. Only three studies evaluated the potential toxicity of biologics’ intranasal delivery, and they all showed that it was safe. This systematic review confirmed that FcRn is expressed in the nasal airway and the olfactory epithelium, and that FcRn may play a role in IgG and/or IgG-derived molecule-transcytosis across the airway epithelium. However, additional research is needed to better characterize the pharmacokinetic and pharmacodynamic properties of biologics after their intranasal delivery. Full article
(This article belongs to the Special Issue Fc Receptors)
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17 pages, 1070 KiB  
Review
Fc-Receptor Targeted Therapies for the Treatment of Myasthenia gravis
by Christian W. Keller, Marc Pawlitzki, Heinz Wiendl and Jan D. Lünemann
Int. J. Mol. Sci. 2021, 22(11), 5755; https://doi.org/10.3390/ijms22115755 - 28 May 2021
Cited by 15 | Viewed by 4796
Abstract
Myasthenia gravis (MG) is an autoimmune disease in which immunoglobulin G (IgG) antibodies (Abs) bind to acetylcholine receptors (AChR) or to functionally related molecules in the postsynaptic membrane at the neuromuscular junction. IgG crystallizable fragment (Fc)-mediated effector functions, such as antibody-dependent complement deposition, [...] Read more.
Myasthenia gravis (MG) is an autoimmune disease in which immunoglobulin G (IgG) antibodies (Abs) bind to acetylcholine receptors (AChR) or to functionally related molecules in the postsynaptic membrane at the neuromuscular junction. IgG crystallizable fragment (Fc)-mediated effector functions, such as antibody-dependent complement deposition, contribute to disease development and progression. Despite progress in understanding Ab-mediated disease mechanisms, immunotherapy of MG remained rather unspecific with corticosteroids and maintenance with immunosuppressants as first choice drugs for most patients. More specific therapeutic IgG Fc-based platforms that reduce serum half-life or effector functions of pathogenic MG-related Abs are currently being developed, tested in clinical trials or have recently been successfully translated into the clinic. In this review, we illustrate mechanisms of action and clinical efficacies of emerging Fc-mediated therapeutics such as neonatal Fc receptor (FcRn)-targeting agents. Furthermore, we evaluate prospects of therapies targeting classical Fc receptors that have shown promising therapeutic efficacy in other antibody-mediated conditions. Increased availability of Fc- and Fc receptor-targeting biologics might foster the development of personalized immunotherapies with the potential to induce sustained disease remission in patients with MG. Full article
(This article belongs to the Special Issue Fc Receptors)
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29 pages, 2391 KiB  
Review
In Translation: FcRn across the Therapeutic Spectrum
by Timothy Qi and Yanguang Cao
Int. J. Mol. Sci. 2021, 22(6), 3048; https://doi.org/10.3390/ijms22063048 - 17 Mar 2021
Cited by 22 | Viewed by 10011
Abstract
As an essential modulator of IgG disposition, the neonatal Fc receptor (FcRn) governs the pharmacokinetics and functions many therapeutic modalities. In this review, we thoroughly reexamine the hitherto elucidated biological and thermodynamic properties of FcRn to provide context for our assessment of more [...] Read more.
As an essential modulator of IgG disposition, the neonatal Fc receptor (FcRn) governs the pharmacokinetics and functions many therapeutic modalities. In this review, we thoroughly reexamine the hitherto elucidated biological and thermodynamic properties of FcRn to provide context for our assessment of more recent advances, which covers antigen-binding fragment (Fab) determinants of FcRn affinity, transgenic preclinical models, and FcRn targeting as an immune-complex (IC)-clearing strategy. We further comment on therapeutic antibodies authorized for treating SARS-CoV-2 (bamlanivimab, casirivimab, and imdevimab) and evaluate their potential to saturate FcRn-mediated recycling. Finally, we discuss modeling and simulation studies that probe the quantitative relationship between in vivo IgG persistence and in vitro FcRn binding, emphasizing the importance of endosomal transit parameters. Full article
(This article belongs to the Special Issue Fc Receptors)
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19 pages, 1194 KiB  
Review
Role of Polymeric Immunoglobulin Receptor in IgA and IgM Transcytosis
by Hao Wei and Ji-Yang Wang
Int. J. Mol. Sci. 2021, 22(5), 2284; https://doi.org/10.3390/ijms22052284 - 25 Feb 2021
Cited by 44 | Viewed by 6821
Abstract
Transcytosis of polymeric IgA and IgM from the basolateral surface to the apical side of the epithelium and subsequent secretion into mucosal fluids are mediated by the polymeric immunoglobulin receptor (pIgR). Secreted IgA and IgM have vital roles in mucosal immunity in response [...] Read more.
Transcytosis of polymeric IgA and IgM from the basolateral surface to the apical side of the epithelium and subsequent secretion into mucosal fluids are mediated by the polymeric immunoglobulin receptor (pIgR). Secreted IgA and IgM have vital roles in mucosal immunity in response to pathogenic infections. Binding and recognition of polymeric IgA and IgM by pIgR require the joining chain (J chain), a small protein essential in the formation and stabilization of polymeric Ig structures. Recent studies have identified marginal zone B and B1 cell-specific protein (MZB1) as a novel regulator of polymeric IgA and IgM formation. MZB1 might facilitate IgA and IgM transcytosis by promoting the binding of J chain to Ig. In this review, we discuss the roles of pIgR in transcytosis of IgA and IgM, the roles of J chain in the formation of polymeric IgA and IgM and recognition by pIgR, and focus particularly on recent progress in understanding the roles of MZB1, a molecular chaperone protein. Full article
(This article belongs to the Special Issue Fc Receptors)
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