title: CD11c/CD18 Dominates Adhesion of Human Monocytes, Macrophages and Dendritic Cells over CD11b/CD18.
abstract: Complement receptors CR3 (CD11b/CD18) and CR4 (CD11c/CD18) belong to the family of beta2 integrins and are expressed mainly by myeloid cell types in humans. Previously, we proved that CR3 rather than CR4 plays a key role in phagocytosis. Here we analysed how CD11b and CD11c participate in cell adhesion to fibrinogen, a common ligand of CR3 and CR4, employing human monocytes, monocyte-derived macrophages (MDMs) and monocyte-derived dendritic cells (MDDCs) highly expressing CD11b as well as CD11c. We determined the exact numbers of CD11b and CD11c on these cell types by a bead-based technique, and found that the ratio of CD11b/CD11c is 1.2 for MDDCs, 1.7 for MDMs and 7.1 for monocytes, suggesting that the function of CD11c is preponderant in MDDCs and less pronounced in monocytes. Applying state-of-the-art biophysical techniques, we proved that cellular adherence to fibrinogen is dominated by CD11c. Furthermore, we found that blocking CD11b significantly enhances the attachment of MDDCs and MDMs to fibrinogen, demonstrating a competition between CD11b and CD11c for this ligand. On the basis of the cell surface receptor numbers and the measured adhesion strength we set up a model, which explains the different behavior of the three cell types.
authors.affiliation: MTA-ELTE Immunology Research Group, Hungarian Academy of Sciences, Budapest, Hungary.
authors.forename: Noémi
authors.identifier: http://orcid.org/0000-0002-2461-1389
authors.initials: N
authors.lastname: Sándor
authors.affiliation: Department of Immunology, Institute of Biology, Faculty of Science, Eötvös Loránd University, Budapest, Hungary.
authors.forename: Szilvia
authors.initials: S
authors.lastname: Lukácsi
authors.affiliation: Department of Biological Physics, Institute of Physics, Faculty of Science, Eötvös Loránd University, Budapest, Hungary.
authors.forename: Rita
authors.initials: R
authors.lastname: Ungai-Salánki
authors.affiliation: Nanobiosensorics "Lendület" Group, Institute of Technical Physics and Material Sciences, Centre for Energy Research, Hungarian Academy of Sciences, Budapest, Hungary.
authors.forename: Norbert
authors.initials: N
authors.lastname: Orgován
authors.affiliation: Department of Biological Physics, Institute of Physics, Faculty of Science, Eötvös Loránd University, Budapest, Hungary.
authors.forename: Bálint
authors.initials: B
authors.lastname: Szabó
authors.affiliation: Nanobiosensorics "Lendület" Group, Institute of Technical Physics and Material Sciences, Centre for Energy Research, Hungarian Academy of Sciences, Budapest, Hungary.
authors.forename: Róbert
authors.initials: R
authors.lastname: Horváth
authors.affiliation: MTA-ELTE Immunology Research Group, Hungarian Academy of Sciences, Budapest, Hungary.|Department of Immunology, Institute of Biology, Faculty of Science, Eötvös Loránd University, Budapest, Hungary.
authors.forename: Anna
authors.initials: A
authors.lastname: Erdei
authors.affiliation: Department of Immunology, Institute of Biology, Faculty of Science, Eötvös Loránd University, Budapest, Hungary.
authors.forename: Zsuzsa
authors.initials: Z
authors.lastname: Bajtay