In silico modeling identifies CD45 as a regulator of IL-2 synergy in the NKG2D-mediated activation of immature human NK cells

Sci Signal. 2017 Jun 27;10(485):eaai9062. doi: 10.1126/scisignal.aai9062.


Natural killer (NK) cells perform immunosurveillance of virally infected and transformed cells, and their activation depends on the balance between signaling by inhibitory and activating receptors. Cytokine receptor signaling can synergize with activating receptor signaling to induce NK cell activation. We investigated the interplay between the signaling pathways stimulated by the cytokine interleukin-2 (IL-2) and the activating receptor NKG2D in immature (CD56bright) and mature (CD56dim) subsets of human primary NK cells using mass cytometry experiments and in silico modeling. Our analysis revealed that IL-2 changed the abundances of several key proteins, including NKG2D and the phosphatase CD45. Furthermore, we found differences in correlations between protein abundances, which were associated with the maturation state of the NK cells. The mass cytometry measurements also revealed that the signaling kinetics of key protein abundances induced by NKG2D stimulation depended on the maturation state and the pretreatment condition of the NK cells. Our in silico model, which described the multidimensional data with coupled first-order reactions, predicted that the increase in CD45 abundance was a major enhancer of NKG2D-mediated activation in IL-2-treated CD56bright NK cells but not in IL-2-treated CD56dim NK cells. This dependence on CD45 was verified by measurement of CD107a mobilization to the NK cell surface (a marker of activation). Our mathematical framework can be used to glean mechanisms underlying synergistic signaling pathways in other activated immune cells.

MeSH terms

  • Animals
  • CD56 Antigen / metabolism
  • Cytokines / metabolism
  • Gene Expression Regulation*
  • Humans
  • Interferon-gamma / metabolism
  • Interleukin-2 / pharmacology*
  • Killer Cells, Natural / immunology*
  • Killer Cells, Natural / metabolism
  • Leukocyte Common Antigens / metabolism*
  • Lymphocyte Activation / drug effects
  • Mice
  • Models, Theoretical
  • NK Cell Lectin-Like Receptor Subfamily K / metabolism*
  • Signal Transduction


  • CD56 Antigen
  • Cytokines
  • Interleukin-2
  • NCAM1 protein, human
  • NK Cell Lectin-Like Receptor Subfamily K
  • Interferon-gamma
  • Leukocyte Common Antigens
  • PTPRC protein, human
  • Ptprc protein, mouse