Document Type

Dissertation - Open Access

Award Date


Degree Name

Doctor of Philosophy (PhD)

Department / School

Chemistry and Biochemistry

First Advisor

Adam D. Hoppe


antibody, Fc receptor, IgG, phagocytosis, Single particle tracking, TIRF microscopy


Therapeutic antibodies are achieving new levels of therapeutic success in treating cancers and immunological disorders by antibody engagement of Fc receptor-directed immune responses. Conversely, inhibiting autoantibody induced Fc receptor activation is an attractive approach to treat autoimmune diseases. Immunoglobulin G (IgG) antibodies are often the principal subclass used in therapeutic antibodies and associated with autoimmune pathologies because of their long circulation and potent effector functions, including activation of the Fcγ Receptor (FcγR). Thus, a thorough understanding of the FcγR activation is required to improve the efficacy of immunotherapies and to mitigate autoimmunities. It is well established that FcγR clustering is required for activation, yet the minimum number of FcγRs and the spatial characteristics of this activation remain incompletely understood. In this dissertation, sophisticated microscopy methods were employed to elucidate how IgG binding to FcγRs changes their diffusion, membrane topographical environment and the recruitment of the essential kinase Syk. Additionally, this dissertation uses single particle tracking methods (SPT) to examine FcγR cluster valency and activation. Major findings from this work include demonstration that clustering of five FcγRs is sufficient for activation on endosomes, but not the plasma membrane. The findings of this dissertation also provide insights into the mechanisms of action of an FcγR inhibitor for IgG-mediated autoimmune diseases that binds three FcγRs. Together, this work represents significant new insights into FcγR activation that may contribute to the field of basic immunology and may impact immunotherapy design strategy.

Library of Congress Subject Headings

Fc receptors.



Number of Pages



South Dakota State University

Included in

Biochemistry Commons



Rights Statement

In Copyright