Purified complement C3b triggers phagocytosis and activation of human neutrophils via complement receptor 1

Boero E, Gorham RD, Francis EA, Brand J, Teng LH, Doorduijn DJ, Ruyken M, Muts RM, Lehmann C, Verschoor A, van Kessel KP, Heinrich V, Rooijakkers SH (2023)

Publication Type: Journal article

Publication year: 2023

Journal

Scientific Reports Nature Publishing Group: Open Access Journals - Option B

Book Volume: 13

Article Number: 274

Journal Issue: 1

DOI: 10.1038/s41598-022-27279-4

Abstract

The complement system provides vital immune protection against infectious agents by labeling them with complement fragments that enhance phagocytosis by immune cells. Many details of complement-mediated phagocytosis remain elusive, partly because it is difficult to study the role of individual complement proteins on target surfaces. Here, we employ serum-free methods to couple purified complement C3b onto E. coli bacteria and beads and then expose human neutrophils to these C3b-coated targets. We examine the neutrophil response using a combination of flow cytometry, confocal microscopy, luminometry, single-live-cell/single-target manipulation, and dynamic analysis of neutrophil spreading on opsonin-coated surfaces. We show that purified C3b can potently trigger phagocytosis and killing of bacterial cells via Complement receptor 1. Comparison of neutrophil phagocytosis of C3b- versus antibody-coated beads with single-bead/single-target analysis exposes a similar cell morphology during engulfment. However, bulk phagocytosis assays of C3b-beads combined with DNA-based quenching reveal that these are poorly internalized compared to their IgG1 counterparts. Similarly, neutrophils spread slower on C3b-coated compared to IgG-coated surfaces. These observations support the requirement of multiple stimulations for efficient C3b-mediated uptake. Together, our results establish the existence of a direct pathway of phagocytic uptake of C3b-coated targets and present methodologies to study this process.

Authors with CRIS profile

Christian Lehmann Department of Dermatology

Involved external institutions

University Medical Centre Utrecht (UMC Utrecht) NL Netherlands (NL) University of California Davis (UCDAVIS) US United States (USA) (US) Klinikum rechts der Isar DE Germany (DE)

How to cite

APA:

Boero, E., Gorham, R.D., Francis, E.A., Brand, J., Teng, L.H., Doorduijn, D.J.,... Rooijakkers, S.H. (2023). Purified complement C3b triggers phagocytosis and activation of human neutrophils via complement receptor 1. Scientific Reports, 13(1). https://dx.doi.org/10.1038/s41598-022-27279-4

MLA:

Boero, Elena, et al. "Purified complement C3b triggers phagocytosis and activation of human neutrophils via complement receptor 1." Scientific Reports 13.1 (2023).

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