Supplementary MaterialsSupplemental Digital Content hs9-3-e308-s001. extension of NKG2C+ NK cells in CMV seropositive individuals. The cytotoxicity receptor NKG2D is Candesartan (Atacand) downregulated, and the killing capacity through this receptor was markedly reduced in CLL-derived NK cells. In contrast, activation via CD16 (FCRIII) led to adequate activation and Candesartan (Atacand) functional responses in CLL-derived NK cells. These findings indicate that NK cells in CLL are not intrinsically defect and still perform effector functions upon adequate activating signaling. Clinical relevance of this finding was shown by treatment with novel nanobody-Fc constructs, which induced cytotoxic responses in both CLL- and HC-derived NK cells via CD16. Our results show that NK cells, in contrast to the T cell compartment, retain their function within the CLL micro-environment, provided that they receive an adequate activating signal. These findings warrant future studies on NK cell mediated immunotherapeutic strategies in CLL. Introduction Chronic lymphocytic leukemia (CLL) is characterized by an acquired dysregulation of the immune system, which results in an increased risk of infections and decreased anti-tumor surveillance.1,2 Especially T cells have been shown to be dysfunctional in CLL, with reduced cytotoxicity, proliferative potential and impaired ability to form immune synapses.3,4 Several novel immunotherapies with impressive activity in lymphoid malignancies (such as immune checkpoint blockade, chimeric antigen receptor (CAR) transduced T cells, and bi-specific antibodies) show disappointing results in CLL.5C9 These disappointing responses might be caused by the reduced function of the effector T cells that are required for the therapeutic effect.3,4 It is therefore of interest to study other immune effector cells to determine Candesartan (Atacand) their therapeutic potential and strategies to recruit them during immunotherapeutic strategies. Natural killer (NK) Candesartan (Atacand) cells play an important role in anti-viral and anti-tumor immune responses.10 NK cells do not express antigen-specific receptors, but instead are regulated by combined signaling through a variety of activating and inhibitory receptors.11,12 Despite their important role in antitumor immunity, little is known about NK cell phenotype or function in CLL. Data on the expression of several activating receptors such as for example NKp30, NKp46, DNAM-1, Compact disc16 and killer-cell immunoglobulin-like receptors (KIR) on NK cells of CLL individuals are inconsistent.13C17 One feasible confounder that could explain inconsistent outcomes on NK cell phenotype in CLL is cytomegalovirus (CMV) disease. CMV disease leaves a footprint for the phenotype from the NK cell area, leading to a rise Rabbit polyclonal to APBB3 in adult NK cells expressing the activating receptor NKG2C, which understand CMV contaminated cells particularly, and increase after CMV reactivation.18C24 We’ve previously shown that CMV-specific Compact disc8+ and Compact disc4+ T cell subsets increase in CLL, whereas their anti-CMV activity is unaffected.25C27 The failing of other the different parts of the disease fighting capability to regulate CMV may explain the development of CMV-specific T cells in CLL; for instance decreased immunosurveillance by NK cells. Nevertheless, it really is unfamiliar whether CMV-related NK cells are extended in CLL individuals presently, further skewing the NK cell phenotype thereby. Like the phenotype of NK cells, there is certainly discrepancy in data for the features of NK cells in CLL. Problems in NK cell cytotoxicity in CLL had been reported years back 1st, although many papers since possess reported NK cell function to become unaffected in CLL also.13C17,28 Discrepancies on NK cell function in CLL could be triggered by the usage of different experimental stimuli, via organic cytotoxicity receptors or antibody-dependent cellular cytotoxicity (ADCC) reactions. If NK cell function in CLL can be maintained, NK cells could possibly be exploited for cellular immunotherapeutic strategies such as bi-specific antibodies and chimeric antigen receptor (CAR) therapy. Nanobodies (Nb) are single variable domains of heavy-chain only antibodies (VHH) derived from Camelidea (eg, camels and llamas). Nb have shown to be attractive therapeutic agents.29,30 By coupling Nb to human IgG1-Fc tails, CD16-mediated ADCC can be induced by these constructs.31,32 Recently a Nb-Fc construct has been described that targets the chemokine receptor CXCR4 (VUN401-Fc). VUN401-Fc has been shown to specifically target CXCR4, block interaction with the receptor and it is ligand CXCL12, and induce NK cell mediated ADCC.31,32 Current standard first-line therapy for CLL includes rituximab, a monoclonal antibody targeting CD20. However, CD20 is often only expressed at low levels on CLL cells, making it a suboptimal therapeutic target.33 Since CXCR4 is abundantly expressed by CLL cells,34 targeting this chemokine receptor may have more therapeutic potential. To determine if autologous NK cells can be used for immunotherapy in CLL, we analyzed NK.