TLR activation of tumor-associated macrophages from ovarian cancer patients triggers cytolytic activity of NK cells

Francesca Bellora, Roberta Castriconi, Alessandra Dondero, Anna Pessino, Alessio Nencioni, Giovanni Liggieri, Lorenzo Moretta, Alberto Mantovani, Alessandro Moretta, Cristina Bottino

Research output: Contribution to journalArticlepeer-review


We analyzed the functional outcome of the interaction between tumor-associated macrophages (TAMs) and natural killer (NK) cells. TAMs from ascites of ovarian cancer patients displayed an alternatively activated functional phenotype (M2) characterized by a remarkably high frequency and surface density of membrane-bound IL-18. Upon TLR engagement, TAMs acquired a classically activated functional phenotype (M1), released immunostimulatory cytokines (IL-12, soluble IL-18), and efficiently triggered the cytolytic activity of NK cells. TAMs also induced the release of IFN-γ from NK cells, which however was significantly lower compared with that induced by in vitro-polarized M2 cells. Most tumor-associated NK cells displayed a CD56bright, CD16neg or CD56bright, CD16dim phenotype, and very poor cytolytic activities, despite an increased expression of the activation marker CD69. They also showed downregulation of DNAM-1, 2B4, and NTB-A activating receptors, and an altered chemokine receptor repertoire. Importantly however, when appropriately stimulated, NK cells from the patients, including those cells isolated from ascites, efficiently killed autologous TAMs that expressed low, "nonprotective" levels of HLA class I molecules. Overall, our data show the existence of a complex tumor microenvironment in which poorly cytolytic/immature NK cells deal with immunosuppressive tumor-educated macrophages.

Original languageEnglish
Pages (from-to)1814-1822
Number of pages9
JournalEuropean Journal of Immunology
Issue number6
Publication statusPublished - 2014


  • Human
  • Natural killer cells
  • Ovarian cancer
  • Tumor-associated macrophages

ASJC Scopus subject areas

  • Immunology
  • Immunology and Allergy


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