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Updated: Jan 20, 2026

Use of a Monocyte Monolayer Assay to Evaluate Fcγ Receptor-mediated Phagocytosis
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Use of a Monocyte Monolayer Assay to Evaluate Fcγ Receptor-mediated Phagocytosis

Published on: January 2, 2017

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The Fab portion of immunoglobulin G contributes to its binding to Fcγ receptor III

Rina Yogo1,2, Yuki Yamaguchi3, Hiroki Watanabe1

  • 1Exploratory Research Center on Life and Living Systems (ExCELLS), National Institutes of Natural Sciences, 5-1 Higashiyama, Myodaiji, Okazaki, 444-8787, Japan.

Scientific Reports
|August 18, 2019
PubMed

Most cells active in the immune system express receptors for antibodies which mediate a variety of defensive mechanisms. These receptors interact with the Fc portion of the antibody and are therefore collectively called Fc receptors. Here, using high-speed atomic force microscopy, we observe interactions of human, humanized, and mouse/human-chimeric immunoglobulin G1 (IgG1) antibodies and their cognate Fc receptor, FcγRIIIa. Our results demonstrate that not only Fc but also Fab positively contributes to the interaction with the receptor. Furthermore, hydrogen/deuterium exchange mass spectrometric analysis reveals that the Fab portion of IgG1 is directly involved in its interaction with FcγRIIIa, in addition to the canonical Fc-mediated interaction. By targeting the previously unidentified receptor-interaction sites in IgG-Fab, our findings could inspire therapeutic antibody engineering.

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