title: Anti-CD20 Therapy Acts via FcγRIIIA to Diminish Responsiveness of Human Natural Killer Cells.
abstract: Natural killer (NK) immune cells mediate antibody-dependent cellular cytotoxicity (ADCC) by aggregating FcγRIIIA/CD16, contributing significantly to the therapeutic effect of CD20 monoclonal antibodies (mAb). In this study, we show that CD16 ligation on primary human NK cells by the anti-CD20 mAb rituximab or ofatumumab stably impairs the spontaneous cytotoxic response attributable to cross-tolerance of several unrelated NK-activating receptors (including NKG2D, DNAM-1, NKp46, and 2B4). Similar effects were obtained from NK cells isolated from patients with chronic lymphocytic leukemia in an autologous setting. NK cells rendered hyporesponsive in this manner were deficient in the ability of these cross-tolerized receptors to phosphorylate effector signaling molecules critical for NK cytotoxicity, including SLP-76, PLCγ2, and Vav1. These effects were associated with long-lasting recruitment of the tyrosine phosphatase SHP-1 to the CD16 receptor complex. Notably, pharmacologic inhibition of SHP-1 with sodium stibogluconate counteracted CD20 mAb-induced NK hyporesponsiveness, unveiling an unrecognized role for CD16 as a bifunctional receptor capable of engendering long-lasting NK cell inhibitory signals. Our work defines a novel mechanism of immune exhaustion induced by CD20 mAb in human NK cells, with potentially negative implications in CD20 mAb-treated patients where NK cells are partly responsible for clinical efficacy.
authors.affiliation: Department of Experimental Medicine, Sapienza University, Rome, Italy.
authors.forename: Cristina
authors.initials: C
authors.lastname: Capuano
authors.affiliation: Department of Molecular Medicine, Istituto Pasteur-Fondazione Cenci-Bolognetti, Fondazione Eleonora Lorillard Spencer Cenci, Sapienza University, Rome, Italy.
authors.forename: Maddalena
authors.initials: M
authors.lastname: Romanelli
authors.affiliation: Department of Molecular Medicine, Istituto Pasteur-Fondazione Cenci-Bolognetti, Fondazione Eleonora Lorillard Spencer Cenci, Sapienza University, Rome, Italy.
authors.forename: Chiara
authors.initials: C
authors.lastname: Pighi
authors.affiliation: Department of Cellular Biotechnology and Hematology, Sapienza University, Rome, Italy. Hematology unit (2U), S. Maria Goretti Hospital/ICOT, AUSL Latina, Latina, Italy.
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Cimino
authors.affiliation: Hematology unit (2U), S. Maria Goretti Hospital/ICOT, AUSL Latina, Latina, Italy.
authors.forename: Angela
authors.initials: A
authors.lastname: Rago
authors.affiliation: Department of Molecular Medicine, Istituto Pasteur-Fondazione Cenci-Bolognetti, Fondazione Eleonora Lorillard Spencer Cenci, Sapienza University, Rome, Italy.
authors.forename: Rosa
authors.initials: R
authors.lastname: Molfetta
authors.affiliation: Department of Molecular Medicine, Istituto Pasteur-Fondazione Cenci-Bolognetti, Fondazione Eleonora Lorillard Spencer Cenci, Sapienza University, Rome, Italy.
authors.forename: Rossella
authors.initials: R
authors.lastname: Paolini
authors.affiliation: Department of Molecular Medicine, Istituto Pasteur-Fondazione Cenci-Bolognetti, Fondazione Eleonora Lorillard Spencer Cenci, Sapienza University, Rome, Italy.
authors.forename: Angela
authors.initials: A
authors.lastname: Santoni
authors.affiliation: Department of Experimental Medicine, Sapienza University, Rome, Italy. ricciarda.galandrini@uniroma1.it.
authors.forename: Ricciarda
authors.initials: R
authors.lastname: Galandrini
mesh_terms: D048868:Adaptor Proteins, Signal Transducing / Q000378:metabolism; D000911:Antibodies, Monoclonal / Q000494:pharmacology*; D061067:Antibodies, Monoclonal, Humanized; D000920:Antibody-Dependent Cell Cytotoxicity / Q000187:drug effects; D045744:Cell Line, Tumor; D002478:Cells, Cultured; D003594:Cytoplasmic Granules / Q000378:metabolism; D004705:Endocytosis; D058851:GPI-Linked Proteins / Q000276:immunology; D006801:Humans; D007108:Immune Tolerance / Q000187:drug effects; D059425:Interferon-gamma Release Tests; D007694:Killer Cells, Natural / Q000187:drug effects* / Q000276:immunology; D015451:Leukemia, Lymphocytic, Chronic, B-Cell / Q000276:immunology; D009895:Opsonin Proteins / Q000276:immunology; D051966:Phospholipase C gamma / Q000378:metabolism; D010750:Phosphoproteins / Q000378:metabolism; D010766:Phosphorylation; D011499:Protein Processing, Post-Translational; D053824:Protein Tyrosine Phosphatase, Non-Receptor Type 6 / Q000037:antagonists & inhibitors / Q000378:metabolism; D051567:Proto-Oncogene Proteins c-vav / Q000378:metabolism; D017452:Receptors, IgG / Q000276:immunology*; D000069283:Rituximab / Q000494:pharmacology*
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D000911:Antibodies, Monoclonal; D061067:Antibodies, Monoclonal, Humanized; C428200:FCGR3B protein, human; D058851:GPI-Linked Proteins; D009895:Opsonin Proteins; D010750:Phosphoproteins; D051567:Proto-Oncogene Proteins c-vav; D017452:Receptors, IgG; C092947:SLP-76 signal Transducing adaptor proteins; C496618:VAV1 protein, human; D000069283:Rituximab; C509249:PTPN6 protein, human; D053824:Protein Tyrosine Phosphatase, Non-Receptor Type 6; D051966:Phospholipase C gamma; C527517:ofatumumab