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Supplementary Figure S9 from Human Tumor–Associated Macrophages and Neutrophils Regulate Antitumor Antibody Efficacy through Lethal and Sublethal Trogocytosis

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posted on 2024-04-01, 07:21 authored by Sunil Singhal, Abhishek S. Rao, Jason Stadanlick, Kyle Bruns, Neil T. Sullivan, Andres Bermudez, Adam Honig-Frand, Ryan Krouse, Sachinthani Arambepola, Emily Guo, Edmund K. Moon, George Georgiou, Thomas Valerius, Steven M. Albelda, Evgeniy B. Eruslanov

Supplementary Figure S9. (A and B) Representative dotplots and summary results showing the ability of TAM pretreated with blocking anti-CD64 F(ab')2 and anti-CD32 F(ab')2 fragments (5ug/ml) to kill PKH67+ A431 cells at a 1:1 E:T ratio in the presence of cetuximab (1ug/ml) in a 12 hrs FACS-based assay. Dead A431 tumor cells were defined as TO-PRO-3+PKH67+ cells. (C and D) Representative dotplots and summary results demonstrating the ability of HLA-A2neg TAM to stimulate of Ly95 cells responses (intracellular IFN-γ) after their preincubation with cetuximab-opsonized A549/HLA-A2+NY-ESO tumor cells at the indicated time points. Kruskal-Wallis multiple comparisons test. Data represented as mean ± SEM. (E) The expression of NY-ESO-1 protein in different batches of transduced A549 tumor cells. The expression of intracellular NY-ESO was evaluated by flow cytometry using NY-ESO-1 mAb (clone D1Q2U) that recognizes endogenous levels of total NY-ESO-1 protein. Non transduced A549 cells were used as a control. (F-H) Representative dotplots and cumulative data showing the ability of HLA-A2+TAM to stimulate of Ly95 cells responses (intracellular IFN-γ) after preincubation with A549/HLA-A2+NY-ESOhi (F) and A549/HLA-A2+NY-ESOlo tumor cells (G) in the presence or absence of cetuximab for 4 hrs. Wilcoxon matched pairs test for groups with (+) or without (-) Ab. * p<0,01. Kruskal-Wallis test for TAM groups co-cultured with A549/HLA-A2+NY-ESOhi or A549/HLA-A2+NY-ESOlo. Data represented as mean ± SEM. FcR+ effectors were freshly isolated for all experiments.

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National Cancer Institute (NCI)

United States Department of Health and Human Services

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Janssen Pharmaceutica (Janssen)

National Institutes of Health (NIH)

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ARTICLE ABSTRACT

The clinical benefits of tumor-targeting antibodies (tAb) are modest in solid human tumors. The efficacy of many tAbs is dependent on Fc receptor (FcR)–expressing leukocytes that bind Fc fragments of tAb. Tumor-associated macrophages (TAM) and neutrophils (TAN) represent the majority of FcR+ effectors in solid tumors. A better understanding of the mechanisms by which TAMs and TANs regulate tAb response could help improve the efficacy of cancer treatments. Here, we found that myeloid effectors interacting with tAb-opsonized lung cancer cells used antibody-dependent trogocytosis (ADT) but not antibody-dependent phagocytosis. During this process, myeloid cells “nibbled off” tumor cell fragments containing tAb/targeted antigen (tAg) complexes. ADT was only tumoricidal when the tumor cells expressed high levels of tAg and the effectors were present at high effector-to-tumor ratios. If either of these conditions were not met, which is typical for solid tumors, ADT was sublethal. Sublethal ADT, mainly mediated by CD32hiCD64hi TAM, led to two outcomes: (i) removal of surface tAg/tAb complexes from the tumor that facilitated tumor cell escape from the tumoricidal effects of tAb; and (ii) acquisition of bystander tAgs by TAM with subsequent cross-presentation and stimulation of tumor-specific T-cell responses. CD89hiCD32loCD64lo peripheral blood neutrophils (PBN) and TAN stimulated tumor cell growth in the presence of the IgG1 anti-EGFR Ab cetuximab; however, IgA anti-EGFR Abs triggered the tumoricidal activity of PBN and negated the stimulatory effect of TAN. Overall, this study provides insights into the mechanisms by which myeloid effectors mediate tumor cell killing or resistance during tAb therapy. The elucidation of the conditions and mechanisms by which human FcR+ myeloid effectors mediate cancer cell resistance and killing during antibody treatment could help develop improved strategies for treating solid tumors.

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