title: Imaging and measuring the biophysical properties of Fc gamma receptors on single macrophages using atomic force microscopy.
abstract: Fc gamma receptors (FcγR), widely expressed on effector cells (e.g., NK cells, macrophages), play an important role in clinical cancer immunotherapy. The binding of FcγRs to the Fc portions of antibodies that are attached to the target cells can activate the antibody-dependent cell-mediated cytotoxicity (ADCC) killing mechanism which leads to the lysis of target cells. In this work, we used atomic force microscopy (AFM) to observe the cellular ultra-structures and measure the biophysical properties (affinity and distribution) of FcγRs on single macrophages in aqueous environments. AFM imaging was used to obtain the topographies of macrophages, revealing the nanoscale cellular fine structures. For molecular interaction recognition, antibody molecules were attached onto AFM tips via a heterobifunctional polyethylene glycol (PEG) crosslinker. With AFM single-molecule force spectroscopy, the binding affinities of FcγRs were quantitatively measured on single macrophages. Adhesion force mapping method was used to localize the FcγRs, revealing the nanoscale distribution of FcγRs on local areas of macrophages. The experimental results can improve our understanding of FcγRs on macrophages; the established approach will facilitate further research on physiological activities involved in antibody-based immunotherapy.
authors.affiliation: State Key Laboratory of Robotics, Shenyang Institute of Automation, Chinese Academy of Sciences, Shenyang 110016, China.
authors.forename: Mi
authors.initials: M
authors.lastname: Li
authors.forename: Lianqing
authors.initials: L
authors.lastname: Liu
authors.forename: Ning
authors.initials: N
authors.lastname: Xi
authors.forename: Yuechao
authors.initials: Y
authors.lastname: Wang
authors.forename: Xiubin
authors.initials: X
authors.lastname: Xiao
authors.forename: Weijing
authors.initials: W
authors.lastname: Zhang
mesh_terms: D000818:Animals; D000911:Antibodies, Monoclonal / Q000276:immunology; D002460:Cell Line; D008264:Macrophages / Q000166:cytology* / Q000276:immunology / Q000648:ultrastructure; D051379:Mice; D018625:Microscopy, Atomic Force / Q000379:methods*; D017452:Receptors, IgG / Q000032:analysis* / Q000276:immunology
chemical_list: D000911:Antibodies, Monoclonal; D017452:Receptors, IgG
keywords: Antibody; Atomic force microscopy; Fc gamma receptor; Immunotherapy; Macrophage