TEM8 Tri-specific Killer Engager binds both tumor and tumor stroma to specifically engage natural killer cell anti-tumor activity.

Background: The tumor microenvironment contains stromal cells, including endothelial cells and fibroblasts, that aid tumor growth and impair immune cell function. Many solid tumors remain difficult to cure because of tumor-promoting stromal cells, but current therapies targeting tumor stromal cells are constrained by modest efficacy and toxicities. TEM8 is a surface antigen selectively upregulated on tumor and tumor stromal cells, endothelial cells and fibroblasts that may be targeted with specific natural killer (NK) cell engagement.

Low-density PD-1 expression on resting human natural killer cells is functional and upregulated after transplantation.

Expression of programmed cell death protein 1 (PD-1) on natural killer (NK) cells has been difficult to analyze on human NK cells. By testing commercial clones and novel anti-PD-1 reagents, we found expression of functional PD-1 on resting human NK cells in healthy individuals and reconstituting NK cells early after allogeneic hematopoietic stem cell transplantation (allo-HSCT). Peripheral blood samples from healthy individuals and transplant recipients were stained for PD-1 expression using the commercial anti-PD-1 clone PD1.

Potent Cytolytic Activity and Specific IL15 Delivery in a Second-Generation Trispecific Killer Engager.

Natural killer (NK) cells are potent immune modulators that can quickly lyse tumor cells and elicit inflammatory responses. These characteristics make them ideal candidates for immunotherapy. However, unlike T cells, NK cells do not possess clonotypic receptors capable of specific antigen recognition and cannot expand via activating receptor signals alone.

161533 TriKE stimulates NK-cell function to overcome myeloid-derived suppressor cells in MDS.

Myelodysplastic syndrome (MDS) is a clonal heterogeneous stem cell disorder driven by multiple genetic and epigenetic alterations resulting in ineffective hematopoiesis. MDS has a high frequency of immune suppressors, including myeloid-derived suppressor cells (MDSCs), that collectively result in a poor immune response. MDSCs in MDS patients express CD155 that ligates the T-cell immunoreceptor with immunoglobulin and ITIM domain (TIGIT) and delivers an inhibitory signal to natural killer (NK) cells.

Adaptive NK Cells Resist Regulatory T-cell Suppression Driven by IL37.

Natural killer (NK) cells are capable of fighting viral infections and cancer. However, these responses are inhibited by immune suppressor cells in the tumor microenvironment. Tumor progression promotes the recruitment and generation of intratumoral regulatory T cells (Treg), associated with a poor prognosis in cancer patients.

Correction: Activating Receptor Signals Drive Receptor Diversity in Developing Natural Killer Cells.

[This corrects the article DOI: 10.1371/journal.pbio.

Activating Receptor Signals Drive Receptor Diversity in Developing Natural Killer Cells.

It has recently been appreciated that NK cells exhibit many features reminiscent of adaptive immune cells. Considerable heterogeneity exists with respect to the ligand specificity of individual NK cells and as such, a subset of NK cells can respond, expand, and differentiate into memory-like cells in a ligand-specific manner. MHC I-binding inhibitory receptors, including those belonging to the Ly49 and KIR families, are expressed in a variegated manner, which creates ligand-specific diversity within the NK cell pool.

Generation of BiKEs and TriKEs to Improve NK Cell-Mediated Targeting of Tumor Cells.

Cancer immunotherapies have gained significant momentum over the past decade, particularly with the advent of checkpoint inhibitors and CAR T-cells. While the latter personalized targeted immunotherapy has revolutionized the field, a need for off-the-shelf therapies remains. The ability of NK cells to quickly lyse antibody-coated tumors and potently secrete cytokines without prior priming has made NK cells ideal candidates for antigen-specific immunotherapy.

UNC-45A Is a Nonmuscle Myosin IIA Chaperone Required for NK Cell Cytotoxicity via Control of Lytic Granule Secretion.

NK cell's killing is a tightly regulated process under the control of specific cytoskeletal proteins. This includes Wiskott-Aldrich syndrome protein, Wiskott-Aldrich syndrome protein-interacting protein, cofilin, Munc13-4, and nonmuscle myosin IIA (NMIIA). These proteins play a key role in controlling NK-mediated cytotoxicity either via regulating the attachment of lytic granules to the actin-based cytoskeleton or via promoting the cytoskeletal reorganization that is requisite for lytic granule release.

Notch signaling at later stages of NK cell development enhances KIR expression and functional maturation.

The Notch signaling pathway plays a substantial role in human NK cell development. However, the role of Notch on killer Ig-like receptor (KIR) upregulation and acquisition of effector function has not been explored. To evaluate how Notch influences terminal differentiation, cord blood-derived NK cells or sorted peripheral blood NK cells were cultured with IL-15 for 7 d with inhibitory or activating Notch signals.

Transcriptional regulation of Munc13-4 expression in cytotoxic lymphocytes is disrupted by an intronic mutation associated with a primary immunodeficiency.

Autosomal recessive mutations in UNC13D, the gene that encodes Munc13-4, are associated with familial hemophagocytic lymphohistiocytosis type 3 (FHL3). Munc13-4 expression is obligatory for exocytosis of lytic granules, facilitating cytotoxicity by T cells and natural killer (NK) cells. The mechanisms regulating Munc13-4 expression are unknown.

Functional NK cell repertoires are maintained through IL-2Rα and Fas ligand.

Acquisition of a functional NK cell repertoire, known as education or licensing, is a complex process mediated through inhibitory receptors that recognize self. We found that NK cells containing self-killer Ig-like receptors for cognate HLA ligand in vivo were less susceptible to apoptosis. In vitro IL-15 withdrawal showed that uneducated NK cells upregulated Bim and Fas.

NK cell CD16 surface expression and function is regulated by a disintegrin and metalloprotease-17 (ADAM17).

The Fc receptor CD16 is present on essentially all CD56(dim) peripheral blood natural killer (NK) cells. Upon recognition of antibody-coated cells it delivers a potent signal to NK cells, which eliminate targets through direct killing and cytokine production. Here we investigated the regulation of CD16 surface expression after NK cell activation.

Tim-3 is an inducible human natural killer cell receptor that enhances interferon gamma production in response to galectin-9.

NK-cell function is regulated by the integration of signals received from activating and inhibitory receptors. Here we show that a novel immune receptor, T-cell Ig and mucin-containing domain-3 (Tim-3), is expressed on resting human NK cells and is up-regulated on activation. The NK92 NK-cell line engineered to overexpress Tim-3 showed a marked increase in IFN-γ production in the presence of soluble rhGal-9 or Raji tumor cells engineered to express Gal-9.

Cutting edge: KIR antisense transcripts are processed into a 28-base PIWI-like RNA in human NK cells.

Killer Ig-like receptors (KIRs) are expressed in a variegated, clonally restricted fashion on NK cells and are important determinants of NK cell function. Although silencing of individual KIR genes is strongly correlated with the presence of CpG dinucleotide methylation within the promoter, the mechanism responsible for silencing has not been identified. Our results show that antisense transcripts mediate KIR transcriptional silencing through a novel PIWI-like 28-base small RNA.

Activated notch supports development of cytokine producing NK cells which are hyporesponsive and fail to acquire NK cell effector functions.

Natural Killer (NK) cells are powerful effectors of cytotoxicity against "stressed" cells. They also produce cytokines and chemokines to activate the adaptive immune response. Understanding NK cell development and maturation may have implications for cancer therapy and for immunity against infections.

The transcription factor c-Myc enhances KIR gene transcription through direct binding to an upstream distal promoter element.

The killer cell immunoglobulin-like receptor (KIR) repertoire of natural killer (NK) cells determines their ability to detect infected or transformed target cells. Although epigenetic mechanisms play a role in KIR gene expression, work in the mouse suggests that other regulatory elements may be involved at specific stages of NK-cell development. Here we report the effects of the transcription factor c-Myc on KIR expression.

Transcriptional characterization of the Notch signaling pathway in rodent multipotent adult progenitor cells.

The Notch signaling pathway is a multifunctional, evolutionarily conserved pathway, which plays an important role in development as well as stem cell biology. Multipotent adult progenitor cells (MAPCs) represent a unique stem cell population, which is capable of differentiating into cell types of the ectodermal, mesodermal and endodermal lineages in vitro, and contribute to most somatic cell types in vivo. Our aim was to characterize the gene expression of Notch signaling elements in rodent MAPCs.

BCR/ABL alters the function of NK cells and the acquisition of killer immunoglobulin-like receptors (KIRs).

Natural killer (NK) cells decrease in function during chronic myelogenous leukemia (CML) progression from chronic phase to blast crisis, and they can become BCR/ABL(+) late in the disease course. To study this altered function, NK92 cells were transduced with the BCR/ABL oncogene. In contrast to the parental cells, which died when deprived of interleukin 2 (IL-2), p210(+) NK92 cells proliferated and survived indefinitely in the absence of IL-2.

Multipotent progenitor cells can be isolated from postnatal murine bone marrow, muscle, and brain.

Objective: Recent studies have shown that cells from bone marrow (BM), muscle, and brain may have greater plasticity than previously known. We have identified multipotent adult progenitor cells (MAPC) in postnatal human and rodent BM that copurify with mesenchymal stem cells (MSC). BM MAPC proliferate without senescence and differentiate into mesodermal, neuroectodermal, and endodermal cell types.

Blockerette-ligated capture T7-amplified RT-PCR, a new method for determining flanking sequences.

We have developed a highly sensitive PCR-based technique termed blockerette-ligated capture T7-amplified reverse-transcription PCR (BCT-RT-PCR), which can be used to characterize unknown proviral flanking sequences from a broad range of samples and depends only on knowing the retroviral sequence. This method incorporates several essential elements to make it both sensitive and specific, including a "blockerette" linker, magnetic capture of target sequences, and exponential replication of potentially rare sequences using a nested promoter for T7 RNA polymerase, followed by nested RT-PCR. This linkage of methods was designed to increase sensitivity by decreasing DNA complexity in favor of specific amplification.

Pluripotency of mesenchymal stem cells derived from adult marrow.

We report here that cells co-purifying with mesenchymal stem cells--termed here multipotent adult progenitor cells or MAPCs--differentiate, at the single cell level, not only into mesenchymal cells, but also cells with visceral mesoderm, neuroectoderm and endoderm characteristics in vitro. When injected into an early blastocyst, single MAPCs contribute to most, if not all, somatic cell types. On transplantation into a non-irradiated host, MAPCs engraft and differentiate to the haematopoietic lineage, in addition to the epithelium of liver, lung and gut.

Multipotent adult progenitor cells from bone marrow differentiate into functional hepatocyte-like cells.

We have derived from normal human, mouse, and rat postnatal bone marrow primitive, multipotent adult progenitor cells (MAPCs) that can differentiate into most mesodermal cells and neuroectodermal cells in vitro and into all embryonic lineages in vivo. Here, we show that MAPCs can also differentiate into hepatocyte-like cells in vitro. Human, mouse, and rat MAPCs, cultured on Matrigel with FGF-4 and HGF, differentiated into epithelioid cells that expressed hepatocyte nuclear factor-3beta (HNF-3beta), GATA4, cytokeratin 19 (CK19), transthyretin, and alpha-fetoprotein by day 7, and expressed CK18, HNF-4, and HNF-1alpha on days 14-28.