Anti-CD20 Therapy Acts via FcγRIIIA to Diminish Responsiveness of Human Natural Killer Cells

Cancer Res. 2015 Oct 1;75(19):4097-108. doi: 10.1158/0008-5472.CAN-15-0781. Epub 2015 Jul 30.


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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adaptor Proteins, Signal Transducing / metabolism
  • Antibodies, Monoclonal / pharmacology*
  • Antibodies, Monoclonal, Humanized
  • Antibody-Dependent Cell Cytotoxicity / drug effects
  • Cell Line, Tumor
  • Cells, Cultured
  • Cytoplasmic Granules / metabolism
  • Endocytosis
  • GPI-Linked Proteins / immunology
  • Humans
  • Immune Tolerance / drug effects
  • Interferon-gamma Release Tests
  • Killer Cells, Natural / drug effects*
  • Killer Cells, Natural / immunology
  • Leukemia, Lymphocytic, Chronic, B-Cell / immunology
  • Opsonin Proteins / immunology
  • Phospholipase C gamma / metabolism
  • Phosphoproteins / metabolism
  • Phosphorylation
  • Protein Processing, Post-Translational
  • Protein Tyrosine Phosphatase, Non-Receptor Type 6 / antagonists & inhibitors
  • Protein Tyrosine Phosphatase, Non-Receptor Type 6 / metabolism
  • Proto-Oncogene Proteins c-vav / metabolism
  • Receptors, IgG / immunology*
  • Rituximab / pharmacology*


  • Adaptor Proteins, Signal Transducing
  • Antibodies, Monoclonal
  • Antibodies, Monoclonal, Humanized
  • FCGR3B protein, human
  • GPI-Linked Proteins
  • Opsonin Proteins
  • Phosphoproteins
  • Proto-Oncogene Proteins c-vav
  • Receptors, IgG
  • SLP-76 signal Transducing adaptor proteins
  • VAV1 protein, human
  • Rituximab
  • PTPN6 protein, human
  • Protein Tyrosine Phosphatase, Non-Receptor Type 6
  • Phospholipase C gamma
  • ofatumumab