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. 2012 May 18;7(5):e36928. doi: 10.1371/journal.pone.0036928

Figure 8. Working model of innate recognition-mediated interaction between NK cells and macrophages during anti-tumor immune response.

Figure 8

As a response to stimulation from TLR3 ligand poly I:C, macrophages up-express surface RAE-1 (NKG2D ligand) and produce soluble IL-12, IL-15, and IFN-β. RAE-1 on surface of macrophages and their cytokines will strongly activate NK cells to produce IFN-γ and up-expression of NKG2D. IFN-γ produced by NK cells will stimulate macrophages in feedback. NK cells after activation will directly attack tumor cells by recognizing tumor’s RAE-1 and indirectly arrest tumor growth by secreting IFN-γ. At the same time, poly I:C-induced up-regulation of NKG2A ligand Qa-1 protects macrophages themselves from cytolysis by NK cells in order to keep the positive feedback loop in the anti-tumor immune response.