Natural Cytotoxicity Receptors NKp46 Research Articles

Umbilical Cord Blood T Cells Express Multiple Natural Cytotoxicity Receptors after IL-15 Stimulation, but Only NKp30 Is Functional

The natural cytotoxicity receptors (NCRs) NKp30, NKp44, and NKp46 are thought to be NK lineage restricted. Herein we show that IL-15 induces NCR expression on umbilical cord blood (UCB) T cells. NCRs were mainly on CD8(+) and CD56(+) UCB T cells. Only NKp30 was functional as demonstrated by degranulation, IFN-gamma release, redirected killing, and apoptosis. Since NCRs require adaptor proteins for function, the expressions of these adaptors were determined. The adaptors used by NKp30 and NKp46, FcepsilonR1gamma and CD3zeta, were detected in UCB T cells. There was a near absence of DAP12, the adaptor for NKp44, consistent with a hypofunctional state. NKp46 was on significantly fewer UCB T cells, possibly accounting for its lack of function. Adult peripheral blood (PB) T cells showed minimal NCR acquisition after culture with IL-15. Since UCB contains a high frequency of naive T cells, purified naive T cells from adult PB were tested. Although NKp30 was expressed on a small fraction of naive PB T cells, it was nonfunctional. In contrast to UCB, PB T cells lacked FcepsilonR1gamma expression. These results demonstrate differences between UCB and PB T cells regarding NCR expression and function. Such findings challenge the concept that NCRs are NK cell specific.

Increased cytotoxicity of CD4+ invariant NKT cells against CD4+CD25hiCD127lo/– regulatory T cells in allergic asthma

CD4+CD25(hi)CD127(lo/-) regulatory T cells (Treg) have been implicated in the resolution of asthma-associated inflammation while the opposite role of CD4+ invariant NKT (iNKT) cells has been the subject of recent investigations. Studies here focused on mechanisms of interaction between CD4+ iNKT cells and Treg to further explore their roles in allergic asthma (AA). Flow cytometry analysis revealed a significant increase in the expression of the natural cytotoxicity receptors NKp30 and NKp46 by CD4+ iNKT cells in AA subjects compared to healthy controls (HC) and non-allergic asthmatics (NA). Subsequent intracellular staining showed that CD4+ iNKT cells also expressed higher levels of granzyme B and perforin in AA than HC. In in vitro killing assays, AA CD4+ iNKT cells selectively killed autologous Treg, but not CD4+CD25- T cells, more potently than HC and NA counterparts. This increased cytotoxicity positively correlated with asthma severity and granzyme B/perforin expression of CD4+ iNKT cells. Furthermore, it could be abrogated by either inhibition of the granzyme B-/perforin-dependent cell death pathway or oral corticosteroid administration. Altogether, these findings suggest that increased cytotoxicity of CD4+ iNKT cells against Treg might contribute to dysfunctional cellular interactions in AA.

Up-regulation of natural killer (NK) cell activating receptors and increase in NK mediated cytotoxicity using interleukin-15 in patients with newly diagnosed acute myeloid leukemia (AML)

3076 Background: NK cell cytotoxicity is tightly controlled through a balance of signals from the functionally opposing activating and inhibitory receptors found on each cell. Interleukin-15 (IL-15) has a major role in NK cell homeostasis. IL-15 induces the differentiation of NK cells from hematopoietic progenitors, stimulates the expansion of peripheral NK cells and supports their survival. Modulation of the relative frequency and intensity of expression of the NK cell receptors by IL-15 may increase NK mediated cytotoxicity in cancer patients. Methods: We investigated the receptor repertoire and measured NK cell activity in the peripheral blood of 21 patients with newly diagnosed AML prior to any treatment and 15 normal donors. Ex-vivo effects of IL-15 on the NK cell repertoire and NK cell cytotoxicity were investigated. Results: The expression of the activating natural cytotoxicity (NCR) receptors NKp30 and NKp46 and the C-type lectin receptors NKG2D and NKG2C were significantly decreased in the AML patients compared to the NK cells of healthy donors (p<0.0001–0.03). Furthermore, NK cytotoxicity was significantly lower (p<0.0003) in the AML patients at diagnosis compared to that of healthy donors. When NK cells obtained from AML patients were cultured with IL-15, expression of the activating receptors was significantly increased compared to pre-culture levels: NKp30, 84 vs 20% p<0.001; NKp44, 71 vs 4% p<0.0001; NKp46, 83 vs 32% p<0.0002; NKG2D 87 vs 43% p<0.01; NKG2C, 58 vs 18% p<0.005. Concomitantly, cytotoxic activity of NK cells sorted from AML patients increased following IL-15 stimulation (790 vs 2211 LU, p<0.05). This IL-15 induced increase in the activity was blocked by neutralizing antibodies against the NK cell activating receptors. Conclusions: We determined that IL-15, a homeostatic NK cell cytokine, can upregulate the expression of the NK activating receptors and concomitantly increase the NK lytic activity in patients with AML. These data support the use of IL-15 as a platform for NK- based therapies for AML patients. No significant financial relationships to disclose.

Direct Binding of Human NK Cell Natural Cytotoxicity Receptor NKp44 to the Surfaces of Mycobacteria and Other Bacteria

Our previous studies demonstrated that Mycobacterium bovis bacillus Calmette-Guérin (BCG) can directly interact with human NK cells and induce the proliferation, gamma interferon production, and cytotoxic activity of such cells without the need for accessory cells. Thus, the aim of the present study was to identify the putative receptor(s) responsible for the recognition of BCG by human NK cells and potentially involved in the activation of NK cells. To this end, we first investigated the surface expression of three NK cell-activating receptors belonging to the natural cytoxicity receptor (NCR) family on highly purified human NK cells upon in vitro direct stimulation with BCG. An induction of the surface expression of NKp44, but not of NKp30 or NKp46, was observed after 3 and 4 days of in vitro stimulation with live BCG. The NKp44 induction involved mainly a particular NK cell subset expressing the CD56 marker at high density, CD56(bright). In order to establish whether NKp44 could directly bind to BCG, whole BCG cells were stained with soluble forms of the three NCRs chimeric for the human immunoglobulin G (IgG) Fc fragment (NKp30-Fc, NKp44-Fc, NKp46-Fc), followed by incubation with a phycoerythrin (PE)-conjugated goat anti-human IgG antibody. Analysis by flow cytometry of the complexes revealed a higher PE fluorescence intensity for BCG incubated with NKp44-Fc than for BCG incubated with NKp30-Fc, NKp46-Fc, or negative controls. The binding of NKp44-Fc to the BCG surface was confirmed with immunogold labeling using transmission electron microscopy, suggesting the presence of a putative ligand(s) for human NKp44 on the BCG cell wall. Similar binding assays performed on a number of gram-positive and gram-negative bacteria revealed a pattern of NKp44-Fc binding restricted to members of the genus Mycobacterium, to the mycobacterium-related species Nocardia farcinica, and to Pseudomonas aeruginosa. Altogether, the results obtained indicate, for the first time, that at least one member of the NCR family (NKp44) may be involved in the direct recognition of bacterial pathogens by human NK cells.

Interleukin-15 Upregulates the Expression of NK-Cell Activating Receptors and Concomitantly Increases the NK Cytotoxicity in Patients with Acute Myeloid Leukemia.

Natural killer (NK) cells lyse malignant cells without prior antigen-specific priming and play a critical role in the innate immune response. A balance of signals from activating and inhibiting receptors expressed on each NK cell controls its activity. The growth, differentiation and survival of NK cells have been found to be dependent on interleukin-15 (IL-15). Using multicolor flow cytometry we investigated the receptor repertoire and also measured the NK cell activity in twenty three patients with newly diagnosed acute myeloid leukemia (AML) prior to any treatment. Further, we investigated the ex-vivo effect of IL-15 on the NK cell repertoire and NK cell cytotoxicity. The percentage of circulating NK cells was lower (p<0.0001) in the AML patients (6%± 0.7, range 1–17%) compared to the NK cells of healthy donors (12%± 1, range 9–17%). The expression of the activating natural cytotoxicity (NCR) receptors NKp30 and NKp46 and the C-type lectin receptors NKG2D and NKG2C was significantly decreased in the AML patients compared to the NK cells of healthy donors: NKp30 24 vs 51% p<0.0001, NKp46 32 vs 73% p<0.0001, NKG2D 43 vs 83% p<0.0001, NKG2C 17 vs 28% p<0.03. In addition, the receptor expression (mean fluorescence intensity, MFI) was also significantly lower in AML patients compared to healthy donors. No significant differences in the expression of the NCR NKp44 and the NK- cell inhibitory receptors were observed. Furthermore, the NK cytotoxicity in the AML patients at diagnosis was significantly lower (p<0.0003) compared to the NK cytotoxicity of healthy donors (4 vs 75 LU). When NK cells obtained from AML patients were cultured with IL-15, significant increases in the expression of the NK- cell activating receptors (Table 1) were observed. The upregulation of the activating receptors was associated with a concomitant significant increase (p<0.001) of the NK cell cytotoxicity (4 vs 70 LU). The data suggest that IL-15, a homeostatic NK cell cytokine, can upregulate the expression of activating receptors and concomitantly increase the NK lytic activity. The use of IL-15 as a platform for NK- based therapies for AML patients should be considered in the future.Table 1The effect of IL-15 on the receptor expression in AML patientsNK cell Activating ReceptorsNK cells in AML pts at diagnosisNK cells in AML pts after IL-15 stimulationp value% positive, MFI% positive, MFINKp3024, 2.684, 6.00.001NKp444, 2.471, 6.70.001NKp4632, 2.683, 70.002NKG2C17, 2.258, 6.90.005NKG2D43, 2.587, 7.80.01

The Expression Level of Ligands for Natural Killer Cell Receptors Predicts Response to Bacillus Calmette-Guerin Therapy: A Pilot Study

Up to 90% of patients with high grade superficial bladder tumors experience tumor recurrence and up to 50% have progression despite bacillus Calmette-Guerin treatment. Natural killer cells have a major role in the mechanism of the response to bacillus Calmette-Guerin but the exact mechanisms are still elusive. The recently discovered natural cytotoxicity receptors are linked to the host response to viral infection and to cancer. We tested the hypothesis that tumor expression of natural cytotoxicity receptor ligands can serve as a predictive factor for the response to intravesical bacillus Calmette-Guerin in patients with nonmuscle invasive, high grade bladder cancer. We developed a histochemical staining method for analysis of the ligands of the 3 known natural cytotoxicity receptors NKp30, NKp44 and NKp46 using genetically engineered fusion proteins and an automated image analysis system. We examined formalin fixed, paraffin embedded sections of specimens of transurethral bladder tumor resection from patients with primary, nonmuscle invasive, high grade bladder cancer who were subsequently treated with bacillus Calmette-Guerin. We compared natural cytotoxicity receptor ligand expression to the response to bacillus Calmette-Guerin immunotherapy. Six of 17 patients (35%) had recurrence despite bacillus Calmette-Guerin treatment. Primary tumors from favorably responding patients expressed higher levels of ligands for all 3 fusion proteins (NKp30, NKp44 and NKp46 p = 0.0026, 0.027 and 0.044, respectively). Bacillus Calmette-Guerin resistant, high grade, nonmuscle invasive bladder tumors express significantly lower levels of ligands of all 3 natural cytotoxicity receptors compared with bacillus Calmette-Guerin responsive tumors. This suggests that down-regulation of these ligands facilitates escape from the bacillus Calmette-Guerin effect. Furthermore, analysis of ligand expression, which can be performed on formalin fixed, paraffin embedded sections, may serve as a new predictive assay for the response to bacillus Calmette-Guerin.

The Requirement for DNAM-1, NKG2D, and NKp46 in the Natural Killer Cell-Mediated Killing of Myeloma Cells

Recent evidence suggests a role for natural killer (NK) cells in the control of multiple myeloma. We show that expression of the NK cell receptor DNAM-1 (CD226) is reduced on CD56(dim) NK cells from myeloma patients with active disease compared with patients in remission and healthy controls. This suggested that this receptor might play a role in NK-myeloma interactions. The DNAM-1 ligands Nectin-2 (CD112) and the poliovirus receptor (PVR; CD155) were expressed by most patient myeloma samples analyzed. NK killing of patient-derived myelomas expressing PVR and/or Nectin-2 was DNAM-1 dependent, revealing a functional role for DNAM-1 in myeloma cell killing. In myeloma cell lines, cell surface expression of PVR was associated with low levels of NKG2D ligands, whereas cells expressing high levels of NKG2D ligands did not express PVR protein or mRNA. Furthermore, NK cell-mediated killing of myeloma cell lines was dependent on either DNAM-1 or NKG2D but not both molecules. In contrast, the natural cytotoxicity receptor NKp46 was required for the killing of all myeloma cell lines analyzed. Thus, DNAM-1 is important in the NK cell-mediated killing of myeloma cells expressing the cognate ligands. The importance of NKp46, NKG2D, and DNAM-1 in myeloma killing mirrors the differential expression of NK cell ligands by myeloma cells, reflecting immune selection during myeloma disease progression.

NKG2D and Natural Cytotoxicity Receptors Are Involved in Natural Killer Cell Interaction with Self‐Antigen Presenting Cells and Stromal Cells

It is thought that human natural killer (NK) lymphocytes should not damage self-tissues due to the inhibiting signal initiated by the engagement of one or another inhibitory receptor superfamily (IRS) members with self-human histocompatibility antigen (HLA)-I. During viral infection, the low expression of self-HLA-I on infected-cells leads to a reduction of the inhibiting signal and thus NK cells kill self-cells (missing self-hypothesis). Here, we have analyzed human NK cell interaction with self-cells as antigen-presenting cells (APC) or stromal cells isolated from bone marrow or skin. Despite the expression of high levels of HLA-I, APC and stromal cells are killed by interleukin (IL)-2-activated NK cells upon lymphocyte function antigen (LFA)1-(intracellular adhesion molecule) (ICAM)1 interaction. The natural cytotoxicity receptors NKp30 and NKp46 are responsible for the delivery of lethal hit to APC, whereas NKG2D-activating receptor, the ligand of the major histocompatibility complex (MHC)-related molecule MICA, and the UL16-binding protein are involved in stromal cell killing. These events are dependent on the activation of phosphoinositol 3-kinase and consequent release of perforins and granzymes. Both bone marrow stromal cells and skin fibroblasts inhibit T cell proliferation to alloantigen or triggering through CD3/T cell receptor complex. Importantly, NK cells can revert this veto effect. Altogether, these findings support the notion that NK cells can recognize self-cells possibly affecting both APC function and interaction between lymphocytes and microenvironment leading to autoreactivity.

Expression of ICP0 Is Sufficient to Trigger Natural Killer Cell Recognition of Herpes Simplex Virus–Infected Cells by Natural Cytotoxicity Receptors

Natural killer (NK) cells are an important component of the immune response to a number of viruses; however, the molecular basis of how NK cells discriminate between healthy and virus-infected cells is largely unknown. Here, we show that expression of the immediate-early gene product ICP0 is sufficient to produce an increased susceptibility to NK lysis of herpes simplex virus (HSV)-infected cells. This effect does not depend on down-regulation of major histocompatibility complex class I molecules or on the induction of expression of ligands for the activating NKG2D receptor. Detection by NK cells of the changes in the target cell induced by HSV ICP0 gene expression depends on the natural cytotoxicity receptors (NCRs) NKp30, NKp44, and NKp46. To our knowledge, this is the first identification of a viral gene that triggers the up-regulation of cellular ligands for the NCR; moreover, these observations highlight the importance of the NCR for immunosurveillance of viral infection by NK cells.

Deficient expression of NCR in NK cells from acute myeloid leukemia: evolution during leukemia treatment and impact of leukemia cells in NCRdull phenotype induction

AbstractNatural killer (NK) cells play an important role in tumor-cell clearance, particularly against leukemia, as shown by killer cell inhibitory receptor (KIR)–mismatched allogeneic stem cell transplantation. Analysis of in vitro IL-2–expanded NK cells from patients with myelocytic/monocytic acute myeloid leukemia (AML-NK cells) has revealed poor cytolytic functions because of deficient expression of pivotal activation molecules—the natural cytotoxicity receptors (NCRs) NKp30, NKp44, and NKp46. To exclude the possibility that this observation was caused by the in vitro amplification of a small NCRdull population, we analyzed the AML-NK phenotype directly, without any in vitro expansion. We first confirmed that the NCRdull phenotype was not an in vitro artifact. Moreover, analysis of a large population of AML patients allowed us to demonstrate that phenotype was not restricted to a French-American-British (FAB) subtype and was not associated with a particular cytogenetic abnormality. Our longitudinal study of AML patients showed that the NCRdull phenotype was acquired during leukemia development because we observed its complete (for NKp46) or partial (for NKp30) reversibility in patients achieving complete remission (CR). Reversibility of the NCRdull phenotype after CR suggested that leukemia cells might be involved in NCR down-regulation. In agreement with this hypothesis, direct contact between leukemic blasts and NK cells (but not leukemia-cell supernatants) induced loss or decrease in NKp30 and NKp46 expression while impeding NKp44 induction by IL-2. We excluded the major implication of TGF-β in NCR down-regulation. Although the clinical antitumor value of NK cells is clearly demonstrated in allogeneic stem cell transplantation, the role of NK cells in autologous transplantation is not proved. Interestingly, we observed a correlation between the NCRdull phenotype and poor survival in AML patients, suggesting that NK-deficient activation caused by NCR down-regulation could play a role in patient outcome. The prognostic value of NCR expression is discussed, and pathophysiologic implication of the NCR phenotype will be further investigated in a larger study.

Activated gammadelta T cells express the natural cytotoxicity receptor natural killer p 44 and show cytotoxic activity against myeloma cells.

gammadelta T cells account for up to 10% of T lymphocytes in the peripheral blood of healthy donors. They can be activated by cytokines such as interleukin (IL)-2, IL-12 and IL-15, express natural killer (NK) cell markers such as NKG2D and show cytotoxic activity against several tumour cells, including multiple myeloma. Here, we present activated polyclonal gammadelta T cells from healthy donors with an NK T cell-like phenotype expressing the natural cytotoxicity receptor NKp44. Natural cytotoxicity receptors NKp30, NKp44 and NKp46 have been regarded as specific NK receptors; only two gammadelta T cell clones described so far expressed NKp 44. Isolated polyclonal gammadelta T cells cultured for 7 days according to the cytokine-induced killer cell (CIK) protocol with additional IL-15 revealed a surface expression of NKp44 of 8+/-7% (n=22). This could be confirmed by detection of NKp 44 mRNA by reverse transcription-polymerase chain reaction (RT-PCR). gammadelta T cells exhibited a marked cytotoxic activity against myeloma cells, which could be reduced by inhibition of NKp44. To our knowledge, this is the first description of the expression of NKp44 on polyclonal gammadelta T cells.

Recognition of Vaccinia Virus-Infected Cells by Human Natural Killer Cells Depends on Natural Cytotoxicity Receptors

Natural Killer (NK) cells are important in the immune response to a number of viruses; however, the mechanisms used by NK cells to discriminate between healthy and virus-infected cells are only beginning to be understood. Infection with vaccinia virus provokes a marked increase in the susceptibility of target cells to lysis by NK cells, and we show that recognition of the changes in the target cell induced by vaccinia virus infection depends on the natural cytotoxicity receptors NKp30, NKp44, and NKp46. Vaccinia virus infection does not induce expression of ligands for the activating NKG2D receptor, nor does downregulation of major histocompatibility complex class I molecules appear to be of critical importance for altered target cell susceptibility to NK cell lysis. The increased susceptibility to lysis by NK cells triggered upon poxvirus infection depends on a viral gene, or genes, transcribed early in the viral life cycle and present in multiple distinct orthopoxviruses. The more general implications of these data for the processes of innate immune recognition are discussed.

Cytolytic function and survival of natural killer cells are severely altered in myelodysplastic syndromes

Natural Killer (NK) cells are critical in host defense against malignant transformation and are potent antileukemic cytotoxic effectors. In the present study, we investigated the peripheral NK function in patients with myelodysplastic syndromes (MDS). We demonstrated that the peripheral NK cell population was quantitatively normal in MDS patients. Furthermore, NK cells displayed an expression of the activating natural cytotoxicity receptors (NCR) NKp46 and NKp30 as well as NKG2D similar to that observed in donors, but exert a highly decreased constitutive cytolytic activity compared to resting normal NK cells. Although activation with IL-2 resulted in the upregulation of NKp46 expression by MDS-NK cells, their cytolytic function remained deeply altered as compared to activated donor NK cells. In addition, MDS NK cells did not proliferate in vitro, and displayed an increased rate of apoptosis in response to IL-2 stimulation although the spontaneous apoptosis was not significantly increased. Interestingly, a proportion of peripheral MDS-NK cells were derived from the MDS clone as the cytogenetic anomaly found in bone marrow karyotype was also detected in 20-50% of circulating NK cells. In conclusion, NK cells' cytolytic function and proliferative capacities in response to activation by cytokines are profoundly altered in MDS.

Antigen Presenting Cells and Stromal Cells Trigger Human Natural Killer Lymphocytes to Autoreactivity: Evidence for the Involvement of Natural Cytotoxicity Receptors (NCR) and NKG2D

Human natural killer (NK) lymphocytes should not damage autologous cells due to the engagement of inhibitory receptor superfamily (IRS) members by HLA-I. Nevertheless, NK cells kill self cells expressing low levels or lacking HLA-I, as it may occur during viral infections (missing-self hypothesis). Herein, we show that human NK cells can be activated upon binding with self antigen presenting cells or stromal cells despite the expression of HLA-I. Indeed, NK cells can kill and produce pro-inflammatory and regulating cytokines as IFN-γ, TNF-α and IL10 during interaction with autologous dendritic cells or bone marrow stromal cells or skin fibroblasts. The killing of antigen presenting and stromal cells is dependent on LFA1/ICAM1 interaction. Further, the natural cytotoxicity receptors (NCR) NKp30 and NKp46 are responsible for the delivery of lethal hit to DC, whereas NKG2D activating receptor, the ligand of the MHC-related molecule MIC-A and the UL16 binding protein, is involved in stromal cell killing. These findings indicate that different activating receptors are involved in cell to self cell interaction. Finally, NK cells can revert the veto effect of stromal cells on mixed lymphocyte reaction further supporting the idea that NK cells may alter the interaction between T lymphocytes and microenvironment leading to autoreactivity.

Phenotypic and cytolytic activity ofMacaca nemestrina natural killer cells isolated from blood and expanded in vitro

Natural killer (NK) cells from nonhuman primates have not been completely characterized, and methods for expanding nonhuman primates NK cells in vitro have been described only in rhesus species. The purpose of this report was to characterize NK cells in pigtail macaques (Macaca nemestrina), a species that is frequently used in studies of transplantation biology/immunology, virology, vaccine development, and reproductive biology. NK cells from Macaca nemestrina peripheral blood were best defined by the expression of CD16 and CD8alpha, and the absence of CD3. Subsets of these cells express CD56, NKp30, and NKp46. An enhanced ability to kill K562 cells was not present in fluorescence activated cell sorted (FACS)-purified CD16-/CD3+ and CD16-/CD56+ cells isolated from fresh peripheral blood. However, FACS-purified CD16+/CD3- and CD16+/CD56- cells were highly efficient killers of K562 cells. Macaca nemestrina NK cells can be expanded by in vitro culturing of FACS-purified CD16+/CD2-/CD3-/CD56- cells, or from peripheral blood cells depleted of cells expressing CD3, CD4, and HLA-DR. Cells in these cultures expand 70-fold after 21 days of culturing. After culturing, these cells express high levels of natural cytotoxicity receptors (NCRs) NKp30 and NKp46. NK cell populations obtained from FACS-purified CD16+/CD3-, CD16+/CD56- cells and CD3/CD4/HLA-DR-depleted cells were highly efficient killers of K562 cells. These data suggest that a population of highly enriched cytolytic NK cells can be obtained from purified CD16+/CD3- and CD16+/CD56- cells obtained from peripheral blood, as well as from cells that have been cultured and expanded from peripheral blood that is depleted of CD3/CD4/HLA-DR-expressing cells.

Optimal Ex-Vivo Expansion (EvE) of Cord Blood (CB) Natural Killer (NK) Cells, NK Cytotoxicity and NK Receptor (NKR) Expression: Potential for CB Adoptive Cellular Immunotherapy (ACI).

CD56+ NK subsets exhibit differential receptor profiles including killer-Ig-like receptors (KIR), C-lectin (NKG2) and natural cytotoxicity receptors (NCR) involved with tumor target recognition which may play a role in ACI for malignancies (Farag et al Blood, 2002). NK cell activation and NK mediated cytolysis is induced by several triggering receptors such as NCR (i.e. NKp44, NKp46) and NKG2 surface receptors like NKG2D (Moretta, et al, Curr Opinion in Immunol, 2004; Marcenaro et al, Eur J Immunol, 2003). UCB is limited by the absence of available donor effector cells (NK, CTL, LAK and NKT cells) for infusion after transplantation for the treatment of minimal residual resistant hematological relapse and/or PTLD (Barker et al, Blood, 2001; Locatelli, et al Blood,1999). We demonstrated the ability to EvE CB in short term culture (48 hrs) with IL-2, IL-7, IL-12 and anti-CD3 (ABCY) cryopreserved, thawed, recryopreserved, rethawed and ex vivo expanded (CTCTE) with significant increase in CD3−/16+/56+ bright/dim subsets expressing KIR3DL1, KIR2DL1/S1, KIR2DL2 and CD94/NKG2A (Ayello/Cairo et al, BBMT, 25a, 2004). In this study, we compared short-term cultures (48 hrs) with prolonged cultures (4 to 10 days) on expansion, maturation and expression of NCR, NKG2, KIR and cytolytic mechanisms in previously cryopreserved CB that were TCTE. CB was cryopreserved and thawed by the NHLBI/COBLT method. (Kurtzberg/Cairo, Transfuison, 2005). Rethawed nonadherent CB cells were cultured (2–10 days) in serum-free medium alone or with anti-CD3 (50 ng/ml, IL-2 (5 ng/ml), IL-7 (10 ng/ml) and IL-12 (10 ng/ml) (ABCY). NK receptor expression (CD94, NKG2C, NKG2D, NKp44, NKp46, KIR2DS4) and intracellular perforin and granzyme B activity were determined by flow cytometry. NK and LAK cytotoxicity was measured by europium release assay. Significant increases were seen in NK activating KIR2DS4 at day 10 vs 2 in ABCY both in CD3−/16+/56+ dim and bright subsets (16.9±0.4 vs 2.1±0.2% and 22.3±0.3 vs 0.9±0.2%, p<0.001, respectively). C-lectin activating receptor CD94/NKG2D was increased at day 7 vs 2 following ABCY EvE (41.4 ±0.43 vs 23.7±2.0 %, p<0.001). A significant increase was seen in NK (CD3−/16+/56+dim) KIR3DL1 subset at day 10 vs 2 (38.3±2.8 vs 18.9±6.3 7%, p<0.05). In contrast, NCR expression in CD3−/16+/56+ dim NKp44 subset was significantly decreasedat day 10 vs 2 of EvE with ABCY (15.2±0.7 vs 27.2±0.7%, p<0.001). A significant decrease was seen in CD3−/16+/56+ dim NKp46 expression following day 10 vs 2 (8.5±0.2 vs 23.5±1.2 %, p<0.001). Perforin expression demonstrated a significant decrease in ABCY at day 10 vs 2 (55.7±1.8 vs 84.3±1.3%, p<0.001) yet increasing levels of granzyme B from day 2 to 10 (25.8±1.8 vs 45.1±1.7%, p<0.0001). A significant increase in CB NK and LAK cytotoxicity was seen in ABCY on day 10 vs 2 (NK: 71.5 ±1.6 vs 53.8±10.3%, p<0.001; LAK: 63.2±0.24 vs 31.8±1.8%, p<0.001). In summary, CB MNC may be thawed at time of CB transplantation, recryopreserved, rethawed and at a later date EvE and activated for 7–10 days to yield viable NK subsets. EvE in ABCY at 10 days yielded increased expression of NK KAR (CD56+dim and bright) and granzyme B expression but decreased NK C-lectin CD94/NKG2D, NCR NKp46 and NKp48 and perforin expression.

Activated natural killer cells from patients with acute myeloid leukemia are cytotoxic against autologous leukemic blasts in NOD/SCID mice

Natural killer (NK) cells are implicated in the surveillance of hematological malignancies. They participate in the immune response against residual acute myeloid leukemia (AML) after hematopoietic stem cell transplantation with partial HLA class I disparity. However, the role of NK cells in autologous leukemia-specific immunity remains poorly understood. We studied the function of NK cells in AML patients at diagnosis. Following isolation, CD56+CD3- cells exhibited a high proliferative potential in vitro in response to interleukin (IL)-2. The polyclonal population of activated AML-NK cells expressed normal levels of the activating receptor NKG2D and the major natural cytotoxicity receptor NKp46. AML-NK cells were highly effective with respect to interferon-gamma production, cytotoxicity against HLA class I-deficient K562 erythroleukemia cells in vitro and retardation of tumor growth in vivo in K562-bearing NOD/SCID mice. Importantly, when AML blasts were injected into NOD/SCID mice, a single dose of adoptively transferred autologous AML-NK cells significantly reduced the AML load by 8-77%. Recognition of AML blasts may be related to the observed upregulation of ligands for NKG2D and natural cytotoxicity receptors in vivo. We conclude that AML patient-derived NK cells are fully functional, in support of exploring the benefit of AML immunotherapy with IL-2-stimulated autologous NK cells.

DC therapy? Let the natural killer answer

Comment on Fauriat et al, page [2186][1] Natural killer cells from the majority of AML patients show defective killing of immature dendritic cells due to low expression of the natural cytotoxicity receptor NKp30. Defective killing of immature DCs leads to the emergence of tolerogenic T cells and

Expression of natural cytotoxicity receptors NKp30, NKp44, and NKp46 mRNAs and proteins by human hematopoietic and non-hematopoietic cells

T-cells and NK cells arise from common pluripotent stem cells, with shared early developmental pathway and surface markers. Distinguishing between them is becoming difficult, but critical for study. A large family of NK cells, including classical NK, NK-T, and NK-CTL exists. Natural cytotoxicity receptors (NKp46, NKp44, NKp30) have been proposed as specific for classical NK cells, but were expressed at protein and mRNA level by CD8 + NK/T cell line SRIK-NKL, suggesting more widespread expression. We investigated and found expression of these markers at the protein and mRNA level in multiple human cell lines.

Polymorphism in the natural cytotoxicity receptors(NCR) NKp30, NKp44 and NKp46 – a preliminary study

Polymorphism in the natural cytotoxicity receptors(NCR) NKp30, NKp44 and NKp46 – a preliminary study