Novel immune functions of fibrinogen
Boehm, Tobias Konrad
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In this thesis, the molecular characteristics of fibrinogen and IgG are reviewed with an overview of their biological functions, and the main cellular receptors for each, β2 integrins and Fcγ receptors reviewed. This provides the background for the experimental studies, which highlight the role of fibrinogen in the response of leukocytes to fimbrial peptides and IgG-antibody coated particles. Therefore, this thesis aims to elucidate novel roles of fibrinogen in immune responses on a molecular level. In the first sections, fibrinogen binding to neutrophils in response to fimbrial peptides is explored with possible effects on cytokine release. In the later sections, a novel interaction between fibrinogen and IgG is described that appears to influence macrophage phagocytosis in a bimodal fashion depending on the fibrinogen concentration during opsonization of particles. As the study further explores this phenomenon at a molecular level, it appears that fibrinogen acts on IgG-mediated phagocytosis by altering IgG binding behavior towards cells and antigens. In summary, this study demonstrates that fibrinogen can modulate host cell-pathogen interactions through a variety of molecular interactions.