4547 Understanding the molecular mechanism of natural killer cell deficiency to improve natural killer cell in vitro differentiation for therapeutics

OBJECTIVES/GOALS: Natural killer (NK) cells are a potential cancer therapeutic but expanding NK cells efficiently in vitro is difficult. Natural killer cell deficiency (NKD), a primary immune deficiency affecting only NK cells, is caused by defects in several DNA replication proteins. By studying NKD we will achieve better NK cell in vitro differentiation. METHODS/STUDY POPULATION: One patient with NKD has a compound heterozygous mutation in the essential DNA replication protein MCM10. We hypothesize that in individuals with NKD, dramatic telomere erosion from abnormal DNA replication leads to premature senescence and the loss of NK cells. To test our hypothesis, we will knockout one allele of MCM10 or over express MCM10 in NK cells isolated from blood. We will then monitor telomere length, expansion and cytotoxic activity of these NK cells. To understand the role of MCM10 in early stages of NK cell development we will deplete MCM10 in induced pluripotent stem cells and differentiate these cells into NK cells. During this differentiation we will monitor progression through NK cell developmental stages as well as telomere length and senescence markers. RESULTS/ANTICIPATED RESULTS: Telomeres insulate chromosomes and induce permanent growth arrest (senescence) when they are critically short. We have demonstrated that depletion of a DNA replication protein causes telomere erosion and increases senescence markers. NK cells have shorter telomeres and lower telomerase expression than other immune cells. We predict, this relatively poor telomere maintenance sensitizes NK cells to telomere loss upon depletion of replication proteins. During in vitro differentiation, we expect NK cell precursors to undergo premature senescence secondary to telomere shortening. Furthermore, we expect supplementation of DNA replication proteins will enhance NK cell expansion and maturation. DISCUSSION/SIGNIFICANCE OF IMPACT: NKD patients have provided the scientific community with clues as to what proteins NK cells rely on for their development. This project aims not only to understand why these proteins are critical, but to harness that information for cellular anti-cancer therapeutics.

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Natural killer cells suppress human erythroid stem cell proliferation in vitro

Blood ◽

10.1182/blood.v63.2.260.260 ◽

1984 ◽

Vol 63 (2) ◽

pp. 260-269 ◽

Cited By ~ 66

Author(s):

KF Mangan ◽

ME Hartnett ◽

SA Matis ◽

A Winkelstein ◽

T Abo

Keyword(s):

Stem Cell ◽

Natural Killer Cell ◽

Nk Cells ◽

Natural Killer ◽

Nk Cell ◽

Killer Cell ◽

Human Natural Killer Cell ◽

Percoll Density Gradient Centrifugation

Abstract To determine the role of natural killer (NK) cells in the regulation of human erythropoiesis, we studied the effects of NK-enriched cell populations on the in vitro proliferation of erythroid stem cells at three different levels of maturation (day 14 blood BFU-E, day 5–6 marrow CFU-E, and day 10–12 marrow BFU-E). NK cells were enriched from blood by Percoll density gradient centrifugation and by fluorescence- activated cell sorting (FACS), using the human natural killer cell monoclonal antibody, HNK-1. The isolated enriched fractions were cocultured with autologous nonadherent marrow cells or blood null cells and erythropoietin in a methylcellulose erythroid culture system. Cells from low-density Percoll fractions (NK-enriched cells) were predominantly large granular lymphocytes with cytotoxic activity against K562 targets 6–10-fold greater than cells obtained from high- density Percoll fractions (NK-depleted cells). In coculture with marrow nonadherent cells (NA) at NK:NA ratios of 2:1, NK-enriched cells suppressed day 5–6 CFU-E to 62% (p less than 0.025) of controls, whereas NK-depleted cells slightly augmented CFU-E to 130% of controls (p greater than 0.05). In contrast, no suppression of day 10–12 marrow BFU-E was observed employing NK-enriched cells. The NK CFU-E suppressor effects were abolished by complement-mediated lysis of NK-enriched cells with the natural killer cell antibody, HNK-1. Highly purified HNK- 1+ cells separated by FACS suppressed marrow CFU-E to 34% (p less than 0.025) and marrow BFU-E to 41% (p less than 0.025) of controls. HNK- cells had no significant effect on either BFU-E or CFU-E growth. NK- enriched cells were poor stimulators of day 14 blood BFU-E in comparison to equal numbers of NK-depleted cells or T cells isolated by E-rosetting (p less than 0.01). Interferon boosting of NK-enriched cells abolished their suboptimal burst-promoting effects and augmented their CFU-E suppressor effects. These studies provide evidence for a potential regulatory role of NK cells in erythropoiesis. The NK suppressor effect is maximal at the level of the mature erythroid stem cell CFU-E. These findings may explain some hypoproliferative anemias that develop in certain NK cell-activated states.

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Natural killer cells suppress human erythroid stem cell proliferation in vitro

Blood ◽

10.1182/blood.v63.2.260.bloodjournal632260 ◽

1984 ◽

Vol 63 (2) ◽

pp. 260-269 ◽

Cited By ~ 1

Author(s):

KF Mangan ◽

ME Hartnett ◽

SA Matis ◽

A Winkelstein ◽

T Abo

Keyword(s):

Stem Cell ◽

Natural Killer Cell ◽

Nk Cells ◽

Natural Killer ◽

Nk Cell ◽

Killer Cell ◽

Human Natural Killer Cell ◽

Percoll Density Gradient Centrifugation

To determine the role of natural killer (NK) cells in the regulation of human erythropoiesis, we studied the effects of NK-enriched cell populations on the in vitro proliferation of erythroid stem cells at three different levels of maturation (day 14 blood BFU-E, day 5–6 marrow CFU-E, and day 10–12 marrow BFU-E). NK cells were enriched from blood by Percoll density gradient centrifugation and by fluorescence- activated cell sorting (FACS), using the human natural killer cell monoclonal antibody, HNK-1. The isolated enriched fractions were cocultured with autologous nonadherent marrow cells or blood null cells and erythropoietin in a methylcellulose erythroid culture system. Cells from low-density Percoll fractions (NK-enriched cells) were predominantly large granular lymphocytes with cytotoxic activity against K562 targets 6–10-fold greater than cells obtained from high- density Percoll fractions (NK-depleted cells). In coculture with marrow nonadherent cells (NA) at NK:NA ratios of 2:1, NK-enriched cells suppressed day 5–6 CFU-E to 62% (p less than 0.025) of controls, whereas NK-depleted cells slightly augmented CFU-E to 130% of controls (p greater than 0.05). In contrast, no suppression of day 10–12 marrow BFU-E was observed employing NK-enriched cells. The NK CFU-E suppressor effects were abolished by complement-mediated lysis of NK-enriched cells with the natural killer cell antibody, HNK-1. Highly purified HNK- 1+ cells separated by FACS suppressed marrow CFU-E to 34% (p less than 0.025) and marrow BFU-E to 41% (p less than 0.025) of controls. HNK- cells had no significant effect on either BFU-E or CFU-E growth. NK- enriched cells were poor stimulators of day 14 blood BFU-E in comparison to equal numbers of NK-depleted cells or T cells isolated by E-rosetting (p less than 0.01). Interferon boosting of NK-enriched cells abolished their suboptimal burst-promoting effects and augmented their CFU-E suppressor effects. These studies provide evidence for a potential regulatory role of NK cells in erythropoiesis. The NK suppressor effect is maximal at the level of the mature erythroid stem cell CFU-E. These findings may explain some hypoproliferative anemias that develop in certain NK cell-activated states.

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A research-driven approach to the identification of novel natural killer cell deficiencies affecting cytotoxic function

Blood ◽

10.1182/blood.2019000925 ◽

2020 ◽

Vol 135 (9) ◽

pp. 629-637

Author(s):

Michael T. Lam ◽

Emily M. Mace ◽

Jordan S. Orange

Keyword(s):

Natural Killer Cell ◽

Nk Cells ◽

Natural Killer ◽

Nk Cell ◽

Killer Cell ◽

Cell Development ◽

Impact Testing ◽

Primary Immune Deficiency ◽

Cell Cytotoxicity ◽

Nk Cell Cytotoxicity

Abstract Natural killer cell deficiencies (NKDs) are an emerging phenotypic subtype of primary immune deficiency. NK cells provide a defense against virally infected cells using a variety of cytotoxic mechanisms, and patients who have defective NK cell development or function can present with atypical, recurrent, or severe herpesviral infections. The current pipeline for investigating NKDs involves the acquisition and clinical assessment of patients with a suspected NKD followed by subsequent in silico, in vitro, and in vivo laboratory research. Evaluation involves initially quantifying NK cells and measuring NK cell cytotoxicity and expression of certain NK cell receptors involved in NK cell development and function. Subsequent studies using genomic methods to identify the potential causative variant are conducted along with variant impact testing to make genotype-phenotype connections. Identification of novel genes contributing to the NKD phenotype can also be facilitated by applying the expanding knowledge of NK cell biology. In this review, we discuss how NKDs that affect NK cell cytotoxicity can be approached in the clinic and laboratory for the discovery of novel gene variants.

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SARS-CoV-2 Spike 1 Protein Controls Natural Killer Cell Activation via the HLA-E/NKG2A Pathway

Cells ◽

10.3390/cells9091975 ◽

2020 ◽

Vol 9 (9) ◽

pp. 1975 ◽

Cited By ~ 2

Author(s):

Daria Bortolotti ◽

Valentina Gentili ◽

Sabrina Rizzo ◽

Antonella Rotola ◽

Roberta Rizzo

Keyword(s):

Epithelial Cells ◽

Nk Cells ◽

Natural Killer ◽

Cell Activation ◽

Nk Cell ◽

Killer Cell ◽

Lung Epithelial Cells ◽

Lung Epithelial ◽

Spike Proteins

Natural killer cells are important in the control of viral infections. However, the role of NK cells during severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection has previously not been identified. Peripheral blood NK cells from SARS-CoV and SARS-CoV-2 naïve subjects were evaluated for their activation, degranulation, and interferon-gamma expression in the presence of SARS-CoV and SARS-CoV-2 spike proteins. K562 and lung epithelial cells were transfected with spike proteins and co-cultured with NK cells. The analysis was performed by flow cytometry and immune fluorescence. SARS-CoV and SARS-CoV-2 spike proteins did not alter NK cell activation in a K562 in vitro model. On the contrary, SARS-CoV-2 spike 1 protein (SP1) intracellular expression by lung epithelial cells resulted in NK cell-reduced degranulation. Further experiments revealed a concomitant induction of HLA-E expression on the surface of lung epithelial cells and the recognition of an SP1-derived HLA-E-binding peptide. Simultaneously, there was increased modulation of the inhibitory receptor NKG2A/CD94 on NK cells when SP1 was expressed in lung epithelial cells. We ruled out the GATA3 transcription factor as being responsible for HLA-E increased levels and HLA-E/NKG2A interaction as implicated in NK cell exhaustion. We show for the first time that NK cells are affected by SP1 expression in lung epithelial cells via HLA-E/NKG2A interaction. The resulting NK cells’ exhaustion might contribute to immunopathogenesis in SARS-CoV-2 infection.

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Adrenergic β1- and β1+2-receptor blockade suppress the natural killer cell response to head-up tilt in humans

Journal of Applied Physiology ◽

10.1152/jappl.1997.83.5.1492 ◽

1997 ◽

Vol 83 (5) ◽

pp. 1492-1498 ◽

Cited By ~ 13

Author(s):

M. Klokker ◽

N. H. Secher ◽

P. Madsen ◽

M. Pedersen ◽

B. K. Pedersen

Keyword(s):

Natural Killer Cell ◽

Nk Cells ◽

Natural Killer ◽

Cell Response ◽

Nk Cell ◽

Killer Cell ◽

Saline Control ◽

Receptor Blockade ◽

Natural Killer Cell Response ◽

Head Up Tilt

Klokker, M., N. H. Secher, P. Madsen, M. Pedersen, and B. K. Pedersen. Adrenergic β1- and β1+2-receptor blockade suppress the natural killer cell response to head-up tilt in humans. J. Appl. Physiol. 83(5): 1492–1498, 1997.—To evaluate stress-induced changes in blood leukocytes with emphasis on the natural killer (NK) cells, eight male volunteers were followed during three trials of head-up tilt with adrenergic β1- (metoprolol) and β1+2- (propranolol) blockade and with saline (control) infusions. The β1- and β1+2-receptor blockade did not affect the appearance of presyncopal symptoms, but the head-up tilt induced a transient lymphocytosis that was abolished by β1+2-receptor blockade but not by β1-receptor blockade. Head-up tilt also resulted in delayed neutrophilia, which was insensitive to β-receptor blockade. Lymphocyte subset analysis revealed that the head-up tilt resulted in a twofold increase in the percentage and absolute number of CD3−/CD16+and CD3−/CD56+NK cells in peripheral blood and that this increase was partially blocked by metoprolol and abolished by propranolol. The NK cell activity on a per NK cell basis did not change during head-up tilt, indicating that the cytotoxic capability of NK cells recruited to circulation is unchanged. The data suggest that the head-up tilt-induced lymphocytosis was due mainly to CD16+and CD56+NK cells and that their recruitment to the blood was inhibited by β1- and especially β1+2-receptor blockade. Thus stress-induced recruitment of lymphocytes, and of NK cells in particular, is mediated by epinephrine through activation of β-receptors on the lymphocytes.

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Elevated CD54 Expression Renders CD4+ T Cells Susceptible to Natural Killer Cell-Mediated Killing

The Journal of Infectious Diseases ◽

10.1093/infdis/jiz413 ◽

2019 ◽

Vol 220 (12) ◽

pp. 1892-1903 ◽

Cited By ~ 1

Author(s):

Xi Chen ◽

Huihui Chen ◽

Zining Zhang ◽

Yajing Fu ◽

Xiaoxu Han ◽

...

Keyword(s):

Immune Response ◽

T Cells ◽

Nk Cells ◽

Natural Killer ◽

Cd4 T Cells ◽

Nk Cell ◽

Killer Cell ◽

Adaptive Immune Response ◽

Phenotypic Analysis

Abstract Background Natural killer (NK) cells are an important type of effector cell in the innate immune response, and also have a role in regulation of the adaptive immune response. Several studies have indicated that NK cells may influence CD4+ T cells during HIV infection. Methods In total, 51 HIV-infected individuals and 15 healthy controls participated in this study. We performed the flow cytometry assays and real-time PCR for the phenotypic analysis and the functional assays of NK cell-mediated deletion of CD4+ T cells, phosphorylation of nuclear factor-κB (NF-κB/p65) and the intervention of metformin. Results Here we detected high CD54 expression on CD4+ T cells in HIV-infected individuals, and demonstrate that upregulated CD54 is associated with disease progression in individuals infected with HIV. We also show that CD54 expression leads to the deletion of CD4+ T cells by NK cells in vitro, and that this is modulated by NF-κB/p65 signaling. Further, we demonstrate that metformin can suppress CD54 expression on CD4+ T cells by inhibiting NF-κB/p65 phosphorylation. Conclusions Our data suggest that further studies to evaluate the potential role of metformin as adjunctive therapy to reconstitute immune function in HIV-infected individuals are warranted.

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Hemostatic Factors Contribute to Tumor Cell Metastatic Potential by a Mechanism Linked to Natural Killer Cell Function.

Blood ◽

10.1182/blood.v104.11.690.690 ◽

2004 ◽

Vol 104 (11) ◽

pp. 690-690 ◽

Cited By ~ 2

Author(s):

Joseph S. Palumbo ◽

Kathryn E. Talmage ◽

Jessica V. Massari ◽

Christine M. La Jeunesse ◽

Matthew J. Flick ◽

...

Keyword(s):

Natural Killer Cell ◽

Tumor Cell ◽

Nk Cells ◽

Natural Killer ◽

Platelet Activation ◽

Cell Function ◽

Nk Cell ◽

Killer Cell ◽

Metastatic Potential ◽

Natural Killer Cell Function

Abstract A linkage between hemostatic system components and tumor cell metastatic potential has been well established, but the underlying mechanism(s) by which various circulating and cell-associated coagulation factors and platelets promote tumor cell dissemination remains to be fully defined. One potential mechanism by which tumor cell-associated microthrombi might enhance metastatic potential is by interfering with the cytolytic elimination of tumor cell emboli by natural killer (NK) cells. In order to explore this hypothesis, we studied tumor dissemination in mice lacking either fibrinogen or Gαq, a G protein critical for platelet activation. Comparative studies of experimental lung metastasis in control and Gαq−/− mice showed that loss of platelet activation resulted in a two-orders-of-magnitude decrease in pulmonary metastatic foci formed by either Lewis lung carcinoma or B16 melanoma. The difference in metastatic success was not the result of differences in tumor growth rate, as tumors transplanted into the dorsal subcutis of Gαq−/− and wildtype animals grew at similar rates. Rather, tumor cell fate analyses using radiolabeled tumor cells showed that the survival of tumor cells within the lung was significantly improved in mice that retained platelet activation function relative to Gαq−/− mice with a profound platelet activation defect. In order to examine the potential interplay between platelet activation and natural killer cell function, we compared pulmonary tumor cell survival in cohorts of control and Gαq−/− mice immuno-depleted of NK cells with an anti-asialo GM1 antibody. Remarkably, platelet function was no longer a determinant of metastatic potential in mice lacking NK cells. Given that fibrin(ogen) is also an established determinant of metastatic success we explored whether the influence of this key hemostatic factor on tumor cell dissemination was also mechanistically-coupled to natural killer cell function. We interbred fibrinogen-deficient mice with Gz-Ly49A transgenic mice known to have a constitutive deficit in NK cells. In those cohorts of mice with normal NK cells, we affirmed the earlier finding that fibrinogen deficiency resulted in a significant diminution in metastatic potential. However, consistent with our findings in mice with defective platelet activation, fibrinogen was found to no longer be a determinant of metastatic potential in mice lacking NK cells. These data establish another important link between innate immune surveillance and the hemostatic system. Further, it appears that at least one mechanism by which tumor cell-associated microthrombi increase metastatic potential is by restricting NK cell-mediated tumor cell elimination. Given that NK cell cytotoxicity requires direct contact with any target cell, one attractive model presently being explored is that tumor cell-associated platelets physically block NK cell access to tumor cell emboli.

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Functional Dichotomy in Natural Killer Cell Signaling

Journal of Experimental Medicine ◽

10.1084/jem.193.12.1413 ◽

2001 ◽

Vol 193 (12) ◽

pp. 1413-1424 ◽

Cited By ~ 67

Author(s):

Francesco Colucci ◽

Eleftheria Rosmaraki ◽

Søren Bregenholt ◽

Sandrine I. Samson ◽

Vincenzo Di Bartolo ◽

...

Keyword(s):

Nk Cells ◽

Natural Killer ◽

Nk Cell ◽

Killer Cell ◽

Surface Receptors ◽

Nk T Cells ◽

Nk Cell Differentiation ◽

Ifn Γ

The product of the protooncogene Vav1 participates in multiple signaling pathways and is a critical regulator of antigen–receptor signaling in B and T lymphocytes, but its role during in vivo natural killer (NK) cell differentiation is not known. Here we have studied NK cell development in Vav1−/− mice and found that, in contrast to T and NK-T cells, the absolute numbers of phenotypically mature NK cells were not reduced. Vav1−/− mice produced normal amounts of interferon (IFN)-γ in response to Listeria monocytogenes and controlled early infection but showed reduced tumor clearance in vivo. In vitro stimulation of surface receptors in Vav1−/− NK cells resulted in normal IFN-γ production but reduced tumor cell lysis. Vav1 was found to control activation of extracellular signal-regulated kinases and exocytosis of cytotoxic granules. In contrast, conjugate formation appeared to be only mildly affected, and calcium mobilization was normal in Vav1−/− NK cells. These results highlight fundamental differences between proximal signaling events in T and NK cells and suggest a functional dichotomy for Vav1 in NK cells: a role in cytotoxicity but not for IFN-γ production.

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Monocytes control natural killer cell differentiation to effector phenotypes

Blood ◽

10.1182/blood-2010-10-312264 ◽

2011 ◽

Vol 117 (17) ◽

pp. 4511-4518 ◽

Cited By ~ 59

Author(s):

Katrina Soderquest ◽

Nick Powell ◽

Carmelo Luci ◽

Nico van Rooijen ◽

Andrés Hidalgo ◽

...

Keyword(s):

Cell Differentiation ◽

Nk Cells ◽

Natural Killer ◽

Nk Cell ◽

Killer Cell ◽

In Vivo Model ◽

Dependent Manner ◽

Nk Cell Differentiation

Abstract Natural killer (NK) cells play a major role in immunologic surveillance of cancer. Whether NK-cell subsets have specific roles during antitumor responses and what the signals are that drive their terminal maturation remain unclear. Using an in vivo model of tumor immunity, we show here that CD11bhiCD27low NK cells migrate to the tumor site to reject major histocompatibility complex class I negative tumors, a response that is severely impaired in Txb21−/− mice. The phenotypical analysis of Txb21-deficient mice shows that, in the absence of Txb21, NK-cell differentiation is arrested specifically at the CD11bhiCD27hi stage, resulting in the complete absence of terminally differentiated CD11bhiCD27low NK cells. Adoptive transfer experiments and radiation bone marrow chimera reveal that a Txb21+/+ environment rescues the CD11bhiCD27hi to CD11bhiCD27low transition of Txb21−/− NK cells. Furthermore, in vivo depletion of myeloid cells and in vitro coculture experiments demonstrate that spleen monocytes mediate the terminal differentiation of peripheral NK cells in a Txb21- and IL-15Rα–dependent manner. Together, these data reveal a novel, unrecognized role for Txb21 expression in monocytes in promoting NK-cell development and help appreciate how various NK-cell subsets are generated and participate in antitumor immunity.

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Potently Cytotoxic Natural Killer Cell Potential Initially Emerges from Erythro-Myeloid Progenitors during Mammalian Development

Blood ◽

10.1182/blood-2019-130347 ◽

2019 ◽

Vol 134 (Supplement_1) ◽

pp. 2464-2464

Author(s):

Carissa Dege ◽

Katherine H Fegan ◽

J Philip Creamer ◽

Melissa M Berrien-Elliott ◽

Stephanie A. Luff ◽

...

Keyword(s):

Nk Cells ◽

Natural Killer ◽

Nk Cell ◽

Fetal Liver ◽

Killer Cell ◽

Hematopoietic Progenitors ◽

Cell Potential ◽

Hematopoietic Stem ◽

Myeloid Progenitor

Natural killer (NK) cells are innate immune cells that target and kill virally infected and malignant cells, making them an attractive target for adoptive immunotherapies. An alternative to donor-derived NK cells is the use of human pluripotent stem cell (hPSC)-derived NK cells, as a renewable "off the shelf" product. Previous studies have identified hPSC-derived NK cells as potently cytotoxic, compared to donor-derived NK cells. As the differentiation of hPSCs mimics early embryonic development, this raises the possibility that hPSC-derived NK cells are ontogenically distinct from adult NK cells. NK cells are present during embryonic hematopoiesis, but their ontogenic origins are poorly understood. NK cells are thought to arise from a common lymphoid progenitor (CLP), lying downstream of hematopoietic stem cells (HSCs), but evidence exists that NK cells may arise from HSC-independent progenitors as NK cells are found in the early murine fetal liver, and NK cell progenitors are found in the early human yolk sac (YS). In this study, we investigated the emergence of NK cells during murine and human embryonic hematopoietic development. During murine embryogenesis, overlapping HSC-independent waves of hematopoietic progenitors occur in the YS that give rise to hematopoietic cells prior to HSC emergence at E10.5. The "primitive" wave occurs at E7.5, followed by an "erythro-myeloid progenitor" (EMP) wave at E8.5. To study NK cell potential during murine YS hematopoiesis, we cultured total YS and sorted hematopoietic progenitors under NK cell promoting conditions. Strikingly, we found that the YS contains NK cell potential. Further, sorted E8.5 kit+CD41+CD16/32+ EMP progenitors, but not primitive hematopoietic progenitors, contain robust NK cell potential. EMP-derived NK (EMP-NK) cells were larger and more granular than adult CLP-derived NK cells. Additionally, NK cells from the E15.5 fetal liver were larger and more granular than NK cells from the adult spleen. Both EMP-NK cells and E15.5 fetal liver NK cells had a more robust degranulation response than their HSC-derived counterparts. Together, these data support the concept that EMP in the YS serve as an initial source of physiologically relevant, functional embryonic NK cells that are phenotypically and functionally distinct from adult NK cells. As hPSC-derived NK cells were described as potently cytotoxic, and we observed that murine HSC-independent NK cells robustly degranulate, we next asked whether NK cell development from hPSCs recapitulates that found in the murine embryo. We have demonstrated previously, using a stage-specific WNT signal manipulation approach that specifies ontogenically distinct hematopoietic progenitors, that hPSC-derived NK cell progenitors can be obtained from two distinct progenitors in vitro. In this study, we sought to better understand the development and function of these two NK cell populations. Stage-specific WNT inhibition (WNTi) during hPSC mesodermal patterning yielded extra-embryonic-like HOXA-/low CD34+ populations that possessed erythroid, myeloid and NK cell potential, but lacked T cell potential. The CD56+ NK cells in these cultures co-emerged with CD15+ granulocytes, indicating that these NK cells may arise from a committed myeloid progenitor. In contrast, HOXA+ CD34+ cells, obtained in a WNT-dependent (WNTd) manner, harbored erythro-myelo-lymphoid multi-lineage potential, including NK cell potential. Phenotypically, WNTi-NK cells were larger, more granular and more mature, compared to WNTd-NK and cord blood (CB)-derived NK cells, reminiscent of murine EMP-NK cells. Further, following multiple stimulation assays, WNTi-NK and WNTd-NK cells had different effector biases. WNTi-NK cells are biased for potent cytotoxic degranulation and exhibited superior cell killing in an ADCC assay. In contrast, WNTd-NK and CB-NK had an attenuated degranulation response, but robustly produced inflammatory cytokines. Finally, RNA-seq analysis demonstrated that WNTd-NK cells were most similar to CB-NK cells. Collectively, these studies identify for the first time that the murine EMP harbor NK cell potential, and these NK cells are functionally unique. These observations raise new questions regarding which ontogenic origin of NK cells should be used in future hPSC-derived adoptive immunotherapy strategies. Disclosures Fehniger: Cyto-Sen Therapeutics: Consultancy; Horizon Pharma PLC: Other: Consultancy (Spouse). Palis:Rubius Therapeutics: Consultancy.

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