Document Type

Thesis - Open Access

Award Date

2021

Degree Name

Master of Science (MS)

Department

Chemistry and Biochemistry

First Advisor

Adam Hoppe

Third Advisor

Antibody, Fcγ receptors, Microcluster, Mobility, Phagocytosis

Abstract

Therapeutic antibodies are rapidly growing class of drugs for treating cancers and immunological disorders by targeting specific antigens or blocking certain pathway to inhibit the tumor growth. In cancer immunotherapy, it was found that Fcγ receptor (FcγR) in immune cells play an important role in antibody dependent cell toxicity against tumor cells. Therefore, understanding FcγR activation mechanism, which requires ligation with immunoglobulin (IgG), is crucial to enhance potency of therapeutic antibodies. One crucial immune responses triggered upon FcγR ligation with IgG is phagocytosis which indicates clearing targets by engulfment. It is known that FcγRs form microclusters which gets rearranged during engagement (J. Lin et al., 2016). Receptor microclustering is important for other immune receptors such as B cell receptor (BCR) and T cell receptor (TCR) (Bolger-Munro et al., 2019; Hashimoto-Tane & Saito, 2016). However, the implications of FcγR rearrangement for antibody-based therapies and cellular effector mechanisms has not been studied. This thesis, examined the dynamics of IgG microclustering and recruitment of Syk kinase to microclusters during antibody dependent cellular phagocytosis (ADCP) using confocal and lattice light sheet (LLS) imaging. Additionally, Total Internal Reflection Fluorescence (TIRF) imaging was used to image the organization of IgG and Syk microclusters during engagement on IgG opsonized supported lipid bilayers (SLBs). The major findings is that surface mobility of the IgG/FcγR complexes enhances ADCP. Moreover, proper Syk and Arp2/3 activity is required for organizing IgG/FcγR complexes during target engulfment and suppressing trogocytic clearance of IgG from the target cell. Together, this study uncovers an important role of antibody mobility in contributing to effective ADCP of target cells.

Format

application/pdf

Number of Pages

81

Publisher

South Dakota State University

Rights

Copyright © 2021 the Author

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