IgG4 subclass antibodies impair antitumor immunity in melanoma
Panagiotis Karagiannis, … , Frank O. Nestle, Sophia N. Karagiannis
Panagiotis Karagiannis, … , Frank O. Nestle, Sophia N. Karagiannis
Published March 1, 2013
Citation Information: J Clin Invest. 2013;123(4):1457-1474. https://doi.org/10.1172/JCI65579.
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Research Article Oncology

IgG4 subclass antibodies impair antitumor immunity in melanoma

Abstract

Host-induced antibodies and their contributions to cancer inflammation are largely unexplored. IgG4 subclass antibodies are present in IL-10–driven Th2 immune responses in some inflammatory conditions. Since Th2-biased inflammation is a hallmark of tumor microenvironments, we investigated the presence and functional implications of IgG4 in malignant melanoma. Consistent with Th2 inflammation, CD22+ B cells and IgG4+-infiltrating cells accumulated in tumors, and IL-10, IL-4, and tumor-reactive IgG4 were expressed in situ. When compared with B cells from patient lymph nodes and blood, tumor-associated B cells were polarized to produce IgG4. Secreted B cells increased VEGF and IgG4, and tumor cells enhanced IL-10 secretion in cocultures. Unlike IgG1, an engineered tumor antigen-specific IgG4 was ineffective in triggering effector cell–mediated tumor killing in vitro. Antigen-specific and nonspecific IgG4 inhibited IgG1-mediated tumoricidal functions. IgG4 blockade was mediated through reduction of FcγRI activation. Additionally, IgG4 significantly impaired the potency of tumoricidal IgG1 in a human melanoma xenograft mouse model. Furthermore, serum IgG4 was inversely correlated with patient survival. These findings suggest that IgG4 promoted by tumor-induced Th2-biased inflammation may restrict effector cell functions against tumors, providing a previously unexplored aspect of tumor-induced immune escape and a basis for biomarker development and patient-specific therapeutic approaches.

Authors

Panagiotis Karagiannis, Amy E. Gilbert, Debra H. Josephs, Niwa Ali, Tihomir Dodev, Louise Saul, Isabel Correa, Luke Roberts, Emma Beddowes, Alexander Koers, Carl Hobbs, Silvia Ferreira, Jenny L.C. Geh, Ciaran Healy, Mark Harries, Katharine M. Acland, Philip J. Blower, Tracey Mitchell, David J. Fear, James F. Spicer, Katie E. Lacy, Frank O. Nestle, Sophia N. Karagiannis

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Figure 6

IgG4 blocks IgG1 antibody-dependent tumor cell killing by inhibiting IgG1 binding and activation through FcγRI.

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IgG4 blocks IgG1 antibody-dependent tumor cell killing by inhibiting IgG...
(A) Competition assay of IgG1 binding on the surface of monocytic cells displaced by addition of increasing concentrations of IgG4 antibody. Proportion of cells binding IgG1 is decreased with increasing concentrations of IgG4, demonstrated by flow cytometric evaluations and representative confocal images (yellow, by ImageStream). (B) Anti-CSPG-4 IgG1-mediated tumor cell killing (by flow cytometry) is inhibited by addition of an antibody known to block IgG Fc binding to FcγRI but not with addition of blocking antibodies to FcγRII or to FcγRIII. (C) Inhibitory functions of anti-CSPG-4 IgG4 are not lost by blocking FcγRII or FcγRIII with previously described specific FcγR blocking antibodies in flow cytometric antibody-dependent tumor cell killing assays. (D) Protein extracts of primary human monocytes isolated by flow cytometric sorting at different times during the antibody-mediated tumor cell killing assay were examined for phosphorylated products of the FcγR signaling pathway. Western blots of phospho-proteins and band density quantifications relative to freshly isolated monocytes demonstrate that IgG4 inhibits the activatory signaling cascades of FcγR (Src, AKT, MEK), while lack of pSHIP implies that FcγRII signaling is not involved in the IgG4 blockade. (B and C) Data are representative figures of 3 independent experiments.