To this end, IL15 short-term PE-NK cells were cultured with autologous PE for different time intervals (2?h, 24?h, 72?h) and their ability to get rid of A549 tumor cells was assessed. cells, cultured for short-time intervals with IL15, maintain the CD56bright phenotype, a high expression of the main activating receptors, produce cytokines and destroy tumor cells similarly to those treated with IL2. Moreover, IL15-triggered PE-NK cells could greatly reduce the growth of founded tumors in mice. This antitumor effect correlated with the ability of IL15-triggered PE-NK cells to traffic from periphery to the tumor site. Finally, we display that IL15 can counteract the inhibitory effect of the tumor pleural microenvironment. Our study suggests that IL15-triggered NK cells isolated from pleural fluid (normally discarded after thoracentesis) may represent a suitable source of effector cells to be used in adoptive immunotherapy of malignancy. following tumor transformation. The function of activating receptors can be counteracted by signals delivered by killer immunoglobulin-like receptors (KIRs) or CD94/NKG2A inhibitory receptors upon connection with HLA-class I molecules, indicated by normal cells but regularly downregulated by tumor cells.5,6,7,8,9,10,11,12,13,14,15,16 Two major NK cell subsets have been identified on the basis of the expression levels of CD56 surface molecules. CD56bright NK cells predominate in cells, express CD94/NKG2A, and secrete numerous cytokines while they may be poorly cytolytic. In contrast, CD56dim cells represent the majority of peripheral blood (PB) NK cells, may express KIRs, are highly cytolytic and may rapidly secrete cytokines upon crosslinking of their activating receptors.17,18,19 To design new therapeutic strategies based on adoptive cell therapy (Take action), many studies analyzed the functional proprieties and the correlation with prognosis of NK cells present in hematological and solid tumors.20,21,22,23 In particular, it has been shown that NK cells play a role in limiting the spreading of metastatic cells. Moreover, in solid tumors, high numbers of peripheral or tumor-associated NK cells correlate with a better prognosis.24-26,27,28,29,30 However, different reports revealed, in non-small cell lung cancers (NSCLCs), renal carcinomas and breast cancers, the presence of tumor-associated CD56bright NK cells that displayed a poor cytolytic activity against tumor cells.25,27,31-33 Inside a earlier study, we analyzed NK cells present in pleural effusions (PE) of main and metastatic tumors of various origins including mesothelioma and lung, breast, colon, gastric, bladder, and uterus carcinomas. In spite of their MK-8998 CD56bright phenotype, PE-NK cells indicated high levels of CD107a upon connection with tumor cells, exposing a high cytolytic potential and indicating that PE-NK cells are not substantially inhibited from the tumor pleural microenvironment. In addition, upon IL2-induced activation, PE-NK cells lysed tumor cells more efficiently than IL2-triggered autologous PB NK cells. These data suggested a possible use of IL2-triggered NK cells to treat main or metastatic pleural tumors by infusing cells systemically or in the pleural cavity.34,35,36 Moreover, the presence of NK cells in PE could also suggest a possible benefit from the infusion of IL2-alone directly in the pleural cavity. In support of this possibility, the results of a earlier study showed that intrapleural IL2 administration, in a patient with PE associated with lymphoma, resulted in a long-lasting (over 2?years) absence of PE.37 On the other hand, several clinical studies based on the systemic infusion of high doses of IL2, showed limited clinical benefits.38,39,40 This is in part related to the fact that IL2 may not only induce proliferation and functional activation of tumor-specific effector cells, but also of regulatory T cells (Treg) leading to the impairment of the therapeutic effect.41,42 In addition, IL2 may induce a severe toxic effect resulting in the vascular leak syndrome.43 Thus, alternative cytokines, capable of effectively boosting NK cells without inducing suppressive loops (such as IL15, IL12, and IL18) are currently being investigated in preclinical cancer models.44,45,46 IL15 is a potent immunostimulating cytokine, potentiating both T and NK cell-mediated immune reactions and promoting the generation MK-8998 of memory space T cells.47,48,49,50 In particular, recent clinical tests identified IL15 as an alternative cytokine (replacing IL2) in the treatment of metastatic melanoma MK-8998 and renal carcinoma.51 Moreover, although different studies suggested that IL12 and IL18, when used alone, display a limited anticancer activity, the combined treatment with IL12 and IL18, revealed the anergic state of tumor-infiltrating NK cells can be reverted.52,53,54 Taken together, these data suggest that the activity of endogenous NK cells can be enhanced from the systemic or community administration of cytokines, such as IL2, IL15, and IL12 plus IL18. Additional strategies include the use of medicines capable of upregulating the activating NK receptors or their ligands on tumor cells, as well as the Rabbit Polyclonal to CDH19 use of obstructing antibodies directed to inhibitory NK receptors.39,55-57 These treatments may be combined with the infusion of clinical-grade cytokines.58 In addition, recent data.