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Wines BD, Trist HM, Esparon S, Impey RE, Mackay GA, Andrews RK, Soares da Costa TP, Pietersz GA, Baker RI, Hogarth PM. Fc Binding by FcγRIIa Is Essential for Cellular Activation by the Anti-FcγRIIa mAbs 8.26 and 8.2. Front Immunol 2021; 12:666813. [PMID: 34759915 PMCID: PMC8573391 DOI: 10.3389/fimmu.2021.666813] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2021] [Accepted: 10/05/2021] [Indexed: 11/21/2022] Open
Abstract
FcγR activity underpins the role of antibodies in both protective immunity and auto-immunity and importantly, the therapeutic activity of many monoclonal antibody therapies. Some monoclonal anti-FcγR antibodies activate their receptors, but the properties required for cell activation are not well defined. Here we examined activation of the most widely expressed human FcγR; FcγRIIa, by two non-blocking, mAbs, 8.26 and 8.2. Crosslinking of FcγRIIa by the mAb F(ab’)2 regions alone was insufficient for activation, indicating activation also required receptor engagement by the Fc region. Similarly, when mutant receptors were inactivated in the Fc binding site, so that intact mAb was only able to engage receptors via its two Fab regions, again activation did not occur. Mutation of FcγRIIa in the epitope recognized by the agonist mAbs, completely abrogated the activity of mAb 8.26, but mAb 8.2 activity was only partially inhibited indicating differences in receptor recognition by these mAbs. FcγRIIa inactivated in the Fc binding site was next co-expressed with the FcγRIIa mutated in the epitope recognized by the Fab so that each mAb 8.26 molecule can contribute only three interactions, each with separate receptors, one via the Fc and two via the Fab regions. When the Fab and Fc binding were thus segregated onto different receptor molecules receptor activation by intact mAb did not occur. Thus, receptor activation requires mAb 8.26 Fab and Fc interaction simultaneously with the same receptor molecules. Establishing the molecular nature of FcγR engagement required for cell activation may inform the optimal design of therapeutic mAbs.
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Affiliation(s)
- Bruce D Wines
- Immune Therapies Laboratory, Burnet Institute, Melbourne, VIC, Australia.,Department of Immunology and Pathology, Central Clinical School, Monash University, Melbourne, VIC, Australia.,Department of Clinical Pathology, The University of Melbourne, Parkville, VIC, Australia
| | - Halina M Trist
- Immune Therapies Laboratory, Burnet Institute, Melbourne, VIC, Australia
| | - Sandra Esparon
- Immune Therapies Laboratory, Burnet Institute, Melbourne, VIC, Australia
| | - Rachael E Impey
- Department of Biochemistry and Genetics, La Trobe Institute for Molecular Science, La Trobe University, Melbourne, VIC, Australia
| | - Graham A Mackay
- Department of Biochemistry and Pharmacology, The University of Melbourne, Parkville, VIC, Australia
| | - Robert K Andrews
- Department Cancer Biology and Therapeutics, John Curtin School of Medical Research, The Australian National University, Canberra, ACT, Australia
| | - Tatiana P Soares da Costa
- Department of Biochemistry and Genetics, La Trobe Institute for Molecular Science, La Trobe University, Melbourne, VIC, Australia
| | - Geoffrey A Pietersz
- Immune Therapies Laboratory, Burnet Institute, Melbourne, VIC, Australia.,Atherothrombosis and Vascular Biology Laboratory, Baker Heart and Diabetes Institute, Melbourne, VIC, Australia
| | - Ross I Baker
- Perth Blood Institute, Murdoch University, Perth, WA, Australia.,Western Australian Centre for Thrombosis and Haemostasis, Murdoch University, Murdoch, WA, Australia
| | - P Mark Hogarth
- Immune Therapies Laboratory, Burnet Institute, Melbourne, VIC, Australia.,Department of Immunology and Pathology, Central Clinical School, Monash University, Melbourne, VIC, Australia.,Department of Clinical Pathology, The University of Melbourne, Parkville, VIC, Australia
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Haimei MA. Concern About the Adverse Effects of Thrombocytopenia and Thrombosis After Adenovirus-Vectored COVID-19 Vaccination. Clin Appl Thromb Hemost 2021; 27:10760296211040110. [PMID: 34541935 PMCID: PMC8642058 DOI: 10.1177/10760296211040110] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Since the outbreak of Covid-19 in December, 2019, scientists worldwide have been
committed to developing COVID-19 vaccines. Only when most people have immunity
to SARS-CoV-2, COVID-19 can reduce even wholly overcome. So far, nine kinds of
COVID-19 vaccines have passed the phase III clinical trials and have approved
for use. At the same time, adverse reactions after COVID-19 vaccination have
also reported. This paper focuses on the adverse effects of thrombosis and
thrombocytopenia caused by the COVID-19 vaccine, especially the
adenovirus-vector vaccine from AstraZeneca and Pfizer, and discusses its
mechanism and possible countermeasures.
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Affiliation(s)
- M A Haimei
- Beijing Tsinghua Changgung Hospital, School of Clinical Medicine, Tsinghua University, Beijing, China
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Anania JC, Chenoweth AM, Wines BD, Hogarth PM. The Human FcγRII (CD32) Family of Leukocyte FcR in Health and Disease. Front Immunol 2019; 10:464. [PMID: 30941127 PMCID: PMC6433993 DOI: 10.3389/fimmu.2019.00464] [Citation(s) in RCA: 77] [Impact Index Per Article: 15.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2018] [Accepted: 02/21/2019] [Indexed: 12/15/2022] Open
Abstract
FcγRs have been the focus of extensive research due to their key role linking innate and humoral immunity and their implication in both inflammatory and infectious disease. Within the human FcγR family FcγRII (activatory FcγRIIa and FcγRIIc, and inhibitory FcγRIIb) are unique in their ability to signal independent of the common γ chain. Through improved understanding of the structure of these receptors and how this affects their function we may be able to better understand how to target FcγR specific immune activation or inhibition, which will facilitate in the development of therapeutic monoclonal antibodies in patients where FcγRII activity may be desirable for efficacy. This review is focused on roles of the human FcγRII family members and their link to immunoregulation in healthy individuals and infection, autoimmunity and cancer.
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Affiliation(s)
- Jessica C Anania
- Centre for Biomedical Research, Burnet Institute, Melbourne, VIC, Australia.,Department of Immunology and Pathology, Central Clinical School, Monash University, Melbourne, VIC, Australia
| | - Alicia M Chenoweth
- Centre for Biomedical Research, Burnet Institute, Melbourne, VIC, Australia.,Department of Immunology and Pathology, Central Clinical School, Monash University, Melbourne, VIC, Australia
| | - Bruce D Wines
- Centre for Biomedical Research, Burnet Institute, Melbourne, VIC, Australia.,Department of Immunology and Pathology, Central Clinical School, Monash University, Melbourne, VIC, Australia.,Department of Pathology, The University of Melbourne, Melbourne, VIC, Australia
| | - P Mark Hogarth
- Centre for Biomedical Research, Burnet Institute, Melbourne, VIC, Australia.,Department of Immunology and Pathology, Central Clinical School, Monash University, Melbourne, VIC, Australia.,Department of Pathology, The University of Melbourne, Melbourne, VIC, Australia
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Wines BD, Tan CW, Duncan E, McRae S, Baker RI, Andrews RK, Esparon S, Gardiner EE, Hogarth PM. Dimeric FcγR ectodomains detect pathogenic anti-platelet factor 4-heparin antibodies in heparin-induced thromobocytopenia. J Thromb Haemost 2018; 16:2520-2525. [PMID: 30269432 PMCID: PMC6635755 DOI: 10.1111/jth.14306] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2018] [Indexed: 11/28/2022]
Abstract
Essentials FcγRIIa mediates life-threatening heparin-induced thrombocytopenia (HIT). Most anti-platelet factor (PF)4-heparin IgGs are not pathogenic so diagnosis of HIT is challenging. Dimeric rsFcγRIIa was used to quantify receptor-binding activity of anti-PF4-heparin antibodies. Dimeric rsFcγRIIa binding specifically correlated with occurrence of HIT. SUMMARY: Background Heparin-induced thrombocytopenia (HIT) is a major and potentially fatal consequence of antibodies produced against platelet factor 4 (PF4)-heparin complexes following heparin exposure. Not all anti-PF4-heparin antibodies are pathogenic, so overdiagnosis can occur, with resulting inappropriate use of alternative anticoagulation therapies that have associated risks of bleeding. However, definitive platelet functional assays are not widely available for routine analysis. Objectives To assess the utility of dimeric recombinant soluble FcγRIIa (rsFcγRIIa) ectodomains for detecting HIT antibodies. Patients/Methods Plasma from 27 suspected HIT patients were tested for pathogenic anti-PF4-heparin antibodies by binding of a novel dimeric FcγRIIa ectodomain probe. Plasmas were also tested by the use of PF4-heparin IgG ELISA, the HemosIL AcuStar HIT IgG-specific assay, and a serotonin release assay (SRA). Results The dimeric rsFcγRIIa test produced no false positives and excluded four samples that were positive by IgG ELISA. In this small patient cohort, the novel assay correctly assigned 93% of the suspected HIT patients, with two of the HIT patients being scored as false negatives. The improved discrimination of the novel assay over the IgG ELISA, which scored four false positives, supports the mechanistic interpretation that binding of dimeric rsFcγRIIa detects pairs of closely spaced IgG antibodies in PF4-heparin immune complexes. Conclusions This study found the cell-free, function-based dimeric rsFcγRIIa assay to be convenient, simple, and potentially predictive of HIT. The assay had improved specificity over the IgG ELISA, and correlated strongly with the AcuStar HIT IgG-specific assay, warranting further evaluation of its potential to identify HIT in larger patient cohorts.
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Affiliation(s)
- B. D. Wines
- Immune Therapies GroupBurnet InstituteMelbourneVictoriaAustralia
- Department of ImmunologyMonash University Central Clinical SchoolMelbourneVictoriaAustralia
- Department of PathologyThe University of MelbourneMelbourneVictoriaAustralia
| | - C. W. Tan
- SA PathologyRoyal Adelaide HospitalAdelaideSouth AustraliaAustralia
| | - E. Duncan
- SA PathologyRoyal Adelaide HospitalAdelaideSouth AustraliaAustralia
| | - S. McRae
- SA PathologyRoyal Adelaide HospitalAdelaideSouth AustraliaAustralia
| | - R. I. Baker
- Murdoch UniversityPerthWestern AustraliaAustralia
| | - R. K. Andrews
- Australian Centre for Blood DiseasesMonash UniversityMelbourneVictoriaAustralia
| | - S. Esparon
- Immune Therapies GroupBurnet InstituteMelbourneVictoriaAustralia
- Department of ImmunologyMonash University Central Clinical SchoolMelbourneVictoriaAustralia
- Department of PathologyThe University of MelbourneMelbourneVictoriaAustralia
| | - E. E. Gardiner
- ACRF Department of Cancer Biology and TherapeuticsJohn Curtin School of Medical ResearchAustralian National UniversityCanberraAustralia
| | - P. M. Hogarth
- Immune Therapies GroupBurnet InstituteMelbourneVictoriaAustralia
- Department of ImmunologyMonash University Central Clinical SchoolMelbourneVictoriaAustralia
- Department of PathologyThe University of MelbourneMelbourneVictoriaAustralia
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