Deletion of the TMEM30A gene enables leukemic cell evasion of NK cell cytotoxicity.

Natural killer (NK) cell immunotherapy has gained attention as a promising strategy for treatment of various malignancies. In this study, we used a genome-wide CRISPR screen to identify genes that provide protection or susceptibility to NK cell cytotoxicity. The screen confirmed the role of several genes in NK cell regulation, such as genes involved in interferon-γ signaling and antigen presentation, as well as genes encoding the NK cell receptor ligands B7-H6 and CD58. Notably, the gene TMEM30A, encoding CDC50A-beta-subunit of the flippase shuttling phospholipids in the plasma membrane, emerged as crucial for NK cell killing. Accordingly, a broad range of TMEM30A knock-out (KO) leukemia and lymphoma cells displayed increased surface levels of phosphatidylserine (PtdSer). TMEM30A KO cells triggered less NK cell degranulation, cytokine production and displayed lower susceptibility to NK cell cytotoxicity. Blockade of PtdSer or the inhibitory receptor TIM-3, restored the NK cell ability to eliminate TMEM30A-mutated cells. The key role of the TIM-3 - PtdSer interaction for NK cell regulation was further substantiated by disruption of the receptor gene in primary NK cells, which significantly reduced the impact of elevated PtdSer in TMEM30A KO leukemic cells. Our study underscores the potential significance of agents targeting the interaction between PtdSer and TIM-3 in the realm of cancer immunotherapy.

ALK fusion NSCLC oncogenes promote survival and inhibit NK cell responses via SERPINB4 expression.

Anaplastic lymphoma kinase (ALK) fusion variants in Non-Small Cell Lung Cancer (NSCLC) consist of numerous dimerizing fusion partners. Retrospective investigations suggest that treatment benefit in response to ALK tyrosine kinase inhibitors (TKIs) differs dependent on the fusion variant present in the patient tumor. Therefore, understanding the oncogenic signaling networks driven by different ALK fusion variants is important. To do this, we developed controlled inducible cell models expressing either Echinoderm Microtubule Associated Protein Like 4 (EML4)-ALK-V1, EML4-ALK-V3, Kinesin Family Member 5B (KIF5B)-ALK, or TRK-fused gene (TFG)-ALK and investigated their transcriptomic and proteomic responses to ALK activity modulation together with patient-derived ALK-positive NSCLC cell lines. This allowed identification of both common and isoform-specific responses downstream of these four ALK fusions. An inflammatory signature that included upregulation of the Serpin B4 serine protease inhibitor was observed in both ALK fusion inducible and patient-derived cells. We show that Signal transducer and activator of transcription 3 (STAT3), Nuclear Factor Kappa B (NF-κB) and Activator protein 1 (AP1) are major transcriptional regulators of SERPINB4 downstream of ALK fusions. Upregulation of SERPINB4 promotes survival and inhibits natural killer cell-mediated cytotoxicity, which has potential for therapeutic impact targeting the immune response together with ALK TKIs in NSCLC.

Histamine dihydrochloride and low-dose interleukin-2 has antileukemic efficacy in NPM1-mutated and myelomonocytic/monocytic acute myeloid leukemia.

Not available.

Single-cell proteo-transcriptomic profiling reveals altered characteristics of stem and progenitor cells in patients receiving cytoreductive hydroxyurea in early-phase chronic myeloid leukemia.

Hydroxyurea (HU) is frequently used in the early phase of chronic myeloid leukemia (CML) to achieve cytoreduction prior to tyrosine kinase inhibitor (TKI) therapy. However, its impact on CML stem and progenitor cells (SPC) remains largely unknown. This study utilized targeted proteo-transcriptomic expression data on 596 genes and 51 surface proteins in 60,000 CD14-CD34+ cells from chronic phase CML patients to determine effects of shortterm HU treatment (4-19 days) on CML SPC. Peripheral blood and bone marrow samples were obtained from 17 CML patients eligible for short-term HU treatment (three patients before and after HU; seven patients before HU; and seven patients after HU) and subjected to single-cell CITE-seq and/or flow cytometry analysis. The analysis revealed enhanced frequencies of hemoglobin-expressing (HBA1, HBA2, HBB) erythroid progenitor cells in blood and bone marrow following HU treatment. In addition, there was an accumulation of cell subsets with S/G2/M phase-related gene and protein expression, likely representing cells arrested in, or progressing slowly through, the cell cycle. The increased frequency of cells in S/G2/M phase after HU was observed already among the most immature leukemic stem cells (LSC), and patients with a high fraction of LSC in the S/G2/M phase showed poor responsiveness to TKI treatment. We conclude that short-term HU treatment entails differentiation of erythroid progenitor cells and alters the characteristics of LSC in CML. The results imply that studies of LSC and progenitor populations in CML should take effects of initial HU therapy into account.

HLA-B*44 and the Bw4-80T motif are associated with poor outcome of relapse-preventive immunotherapy in acute myeloid leukemia.

HLA-B alleles are associated with outcomes in various pathologies, including autoimmune diseases and malignancies. The encoded HLA-B proteins are pivotal in antigen presentation to cytotoxic T cells, and some variants containing a Bw4 motif also serve as ligands to the killer immunoglobulin-like receptors (KIR) 3DL1/S1 of NK cells. We investigated the potential impact of HLA-B genotypes on the efficacy of immunotherapy for relapse prevention in acute myeloid leukemia (AML). Seventy-eight non-transplanted AML patients receiving HDC/IL-2 in the post-consolidation phase were genotyped for HLA-B and KIR genes. HLA-B*44 heralded impaired LFS (leukemia-free survival) and overall survival (OS), but the negative association with outcome was not shared across alleles of the HLA-B44 supertype. Notably, HLA-B*44 is one of few HLA-B44 supertype alleles containing a Bw4 motif with a threonine at position 80, which typically results in weak binding to the inhibitory NK receptor, KIR3DL1. Accordingly, a strong interaction between KIR3DL1 and Bw4 was associated with superior LFS and OS (p = 0.014 and p = 0.027, respectively). KIR3DL1+ NK cells from 80 T-Bw4 donors showed significantly lower degranulation responses and cytokine responses than NK cells from 80I-Bw4 donors, suggesting impaired KIR3DL1-mediated education in 80 T-Bw4 subjects. We propose that presence of a strong KIR3DL1+-Bw4 interaction improves NK cell education and thus is advantageous in AML patients receiving HDC/IL-2 immunotherapy for relapse prevention.

The HLA-B -21 dimorphism impacts on NK cell education and clinical outcome of immunotherapy in acute myeloid leukemia.

Natural killer (NK) cell function is regulated by inhibitory receptors, such as the family of killer immunoglobulin-like receptors (KIRs) and the NKG2A/CD94 heterodimer. These receptors recognize cognate HLA class I molecules on potential target cells, and recent studies imply that an HLA-B dimorphism at position -21 in the gene segment encoding the leader peptide dictates whether NK cell regulation primarily relies on the KIRs or the NKG2A/CD94 receptor. The impact of this HLA-B dimorphism on NK cell-mediated destruction of leukemic cells or on the course of leukemia is largely unknown. In a first part of this study, we compared functions of NK cells in subjects carrying HLA-B -21M or 21T using interleukin-2 (IL-2)-activated NK cells and leukemic cells from patients with acute myeloid leukemia (AML). Subjects carrying HLA-B -21M harbored better-educated NKG2A+ NK cells and displayed superior capacity to degranulate lytic granules against KIR ligand-matched primary leukemic blasts. Second, we aimed to define the potential impact of HLA-B -21 variation on the course of AML in a phase 4 trial in which patients received IL-2-based immunotherapy. In keeping with the hypothesis that 21M may be associated with improved NK cell functionality, we observed superior leukemia-free survival and overall survival in -21M patients than in -21T patients during IL-2-based immunotherapy. We propose that genetic variation at HLA-B -21 may determine the antileukemic efficacy of activated NK cells and the clinical benefit of NK cell-activating immunotherapy.

Long-term (52-week) efficacy and safety of dapagliflozin as an adjunct to insulin therapy in Japanese patients with type 1 diabetes: Subgroup analysis of the DEPICT-2 study.

AIM: To examine the long-term efficacy and safety of dapagliflozin, a sodium-glucose co-transporter-2 (SGLT2) inhibitor used to treat type 1 diabetes, in the Japanese subpopulation of the DEPICT-2 study. MATERIALS AND METHODS: Patients with type 1 diabetes were randomized to dapagliflozin 5 mg (n = 55), dapagliflozin 10 mg (n = 41) or placebo (n = 58) plus insulin for a 24-week, double-blind period followed by a 28-week, single-blind extension phase. RESULTS: From baseline to 24 weeks, dapagliflozin reduced HbA1c compared with placebo (mean change of -0.58% and -0.80% for 5 and 10 mg, respectively), and an HbA1c reduction was observed up to 52 weeks. Compared with placebo, dapagliflozin 5 and 10 mg increased the proportion of patients achieving HbA1c reductions of 0.5% or more without severe hypoglycaemia events and reduced glycaemic variability assessed via continuous glucose monitoring. Both dapagliflozin doses decreased body weight and total daily insulin dose at 24 weeks compared with placebo; these reductions were maintained up to 52 weeks. Diabetic ketoacidosis occurred in both dapagliflozin groups (one and two cases, respectively) but not with placebo. CONCLUSIONS: Efficacy and safety results from the Japanese subpopulation of the DEPICT-2 study were generally consistent with those from the overall population, indicating that long-term dapagliflozin adjunct to insulin therapy improves glycaemic control without an increased risk of hypoglycaemia but with a risk of diabetic ketoacidosis in Japanese patients with type 1 diabetes.

Long-term efficacy and safety of dapagliflozin in patients with inadequately controlled type 1 diabetes: pooled 52-week outcomes from the DEPICT-1 and -2 studies.

AIM: To evaluate the efficacy and safety of adjunct dapagliflozin therapy in patients with type 1 diabetes (T1D). MATERIALS AND METHODS: DEPICT-1 and -2 were randomized, double-blind, parallel-group, 24-week studies, with 28-week extension periods. Adults with T1D and HbA1c 7.5%-10.5% were randomized (1:1:1) to receive dapagliflozin 5 mg, 10 mg or placebo. The short- and long-term efficacy and safety of dapagliflozin were examined in an exploratory pooled analysis of both studies. RESULTS: Efficacy analyses included 530, 529 and 532 and safety analysis included 548, 566 and 532 patients in the dapagliflozin 5 mg, 10 mg and placebo groups, respectively. Baseline characteristics were similar between treatment groups. At week 24, reductions were seen with dapagliflozin 5 and 10 mg compared with placebo in HbA1c (-0.40%, -0.43% vs. 0.00%) and body weight (-2.45, -2.91 vs. 0.11 kg). HbA1c and body weight reductions versus placebo were also seen after 52 weeks of treatment. There was no imbalance in occurrence of severe hypoglycaemic events between groups. The proportion of patients experiencing definite diabetic ketoacidosis (DKA) was higher with dapagliflozin 5 mg (4.0%) and 10 mg (3.5%) compared with placebo (1.1%) over 52 weeks; most events were of mild or moderate severity, and all resolved with treatment. CONCLUSIONS: Over 52 weeks, dapagliflozin provided glycaemic and weight benefits, with no increased frequency of severe hypoglycaemia compared with placebo. More DKA events were reported with dapagliflozin than placebo, highlighting the importance of appropriate patient selection, education and risk-mitigation strategies.

Long-term efficacy and safety of dapagliflozin in patients with inadequately controlled type 1 diabetes (the DEPICT-2 study): 52-week results from a randomized controlled trial.

AIM: To investigate the long-term efficacy and safety of dapagliflozin as an adjunct to adjustable insulin in adults with type 1 diabetes (T1D) and inadequate glycaemic control. MATERIALS AND METHODS: Dapagliflozin Evaluation in Patients with Inadequately Controlled Type 1 Diabetes (DEPICT-2) was a placebo-controlled, double-blind, multicentre, phase III study of adults with T1D (HbA1c 7.5%-10.5%) randomized (1:1:1) to receive dapagliflozin 5, 10 mg, or placebo. The efficacy and safety of dapagliflozin over 52 weeks were exploratory endpoints in this extension to DEPICT-2. RESULTS: Of 813 participants randomized, 88.2% completed the study. From baseline to 52 weeks, dapagliflozin 5 and 10 mg were associated with reduction in HbA1c (difference [95% CI] vs. placebo: -0.20% [-0.34, -0.06] and -0.25% [-0.38, -0.11], respectively) and adjusted mean percentage change in body weight (difference [95% CI] vs. placebo: -4.42% [-5.19, -3.64] and -4.86% [-5.63, -4.08], respectively). Serious adverse events were reported in the dapagliflozin 5, 10 mg, and placebo groups (32 [11.8%], 19 [7.0%] and 16 [5.9%], respectively). The proportion of hypoglycaemic events was similar across groups; severe hypoglycaemia was uncommon. More participants with events adjudicated as definite diabetic ketoacidosis (DKA) were in the dapagliflozin 5 and 10 mg groups versus placebo (11 [4.1%], 10 [3.7%] and 1 [0.4%], respectively); the majority of events were mild or moderate in severity and all were resolved with treatment. CONCLUSIONS: Dapagliflozin led to long-term reductions in HbA1c and body weight in adults with T1D, but increased DKA risk compared with placebo.

Efficacy and safety of dapagliflozin in Japanese patients with inadequately controlled type 1 diabetes (DEPICT-5): 52-week results from a randomized, open-label, phase III clinical trial.

AIMS: To investigate the safety and tolerability of 5 and 10 mg dapagliflozin added to insulin therapy over 52 weeks in Japanese patients with inadequately controlled type 1 diabetes mellitus (T1DM). MATERIALS AND METHODS: This randomized, open-label, parallel-group, multicentre phase III clinical trial was conducted from October 26, 2015 to June 15, 2017. The primary endpoint was the occurrence of adverse events such as hypoglycaemia and diabetic ketoacidosis. Secondary endpoints included changes in glycaemic parameters, total daily insulin dosage and body weight over time. The efficacy of dapagliflozin in patients stratified by body mass index (BMI) <25.0 and ≥25.0 kg/m2 was evaluated in a subgroup analysis. RESULTS: In total, 151 patients received 5 mg (n = 76) or 10 mg (n = 75) dapagliflozin once daily for 52 weeks. Adverse events were observed in 88.2% and 73.3% of patients in the 5 and 10 mg dapagliflozin groups, respectively. Severe hypoglycaemia was reported in 2.6% (n = 2) and 6.7% (n = 5) of patients, and diabetic ketoacidosis in 2.6% (n = 2) and 1.3% (n = 1) of patients in the 5 and 10 mg dapagliflozin groups, respectively. The adjusted mean (95% confidence interval) changes in glycated haemoglobin at week 52 were -0.33% (-0.50, -0.15) and -0.36% (-0.53, -0.18) in the 5 and 10 mg dapagliflozin groups, respectively. There were no differences in efficacy parameters when stratified by BMI. CONCLUSIONS: This study demonstrated the long-term safety and tolerability of dapagliflozin added to insulin therapy in Japanese patients with inadequately controlled T1DM.

Benefit/risk profile of dapagliflozin 5 mg in the DEPICT-1 and -2 trials in individuals with type 1 diabetes and body mass index ≥27 kg/m2.

AIM: The DEPICT-1 and -2 studies (NCT02268214, NCT02460978) evaluated the efficacy and safety of dapagliflozin in individuals with type 1 diabetes who were receiving intensive insulin therapy. The DEPICT-1 and -2 studies (NCT02268214, NCT02460978) evaluated the efficacy and safety of dapagliflozin in individuals with type 1 diabetes. This post-hoc study investigated the safety and efficacy of dapagliflozin in individuals with BMI ≥27 kg/m2 to assess if the benefit/risk ratio associated with dapagliflozin treatment can be further improved than that observed in the overall DEPICT population. METHODS: Changes in glycated haemoglobin (HbA1c) and body weight, percentage change in daily insulin dose and proportion of participants achieving HbA1c reduction ≥0.5% without severe hypoglycaemia were evaluated at weeks 24 and 52. Changes in mean interstitial glucose, mean amplitude of glycaemic excursions and time in target glycaemic range were evaluated at week 24. Safety was assessed until week 56. RESULTS: Week-52 adjusted mean (SE) change from baseline for HbA1c was -0.26% (0.05) with dapagliflozin versus +0.08% (0.05) with placebo and for body weight was -2.74 kg (0.25) with dapagliflozin versus +0.81 kg (0.26) with placebo. Mean (SE) percentage change in daily insulin dose was -10.5% (1.23) with dapagliflozin versus -1.4% (1.36) with placebo. Time spent in target glycaemic range increased by 2.2 h/day versus placebo. Dapagliflozin was well tolerated, with fewer participants experiencing diabetic ketoacidosis (dapagliflozin, 1.7%; placebo, 1.0%) than dapagliflozin 5 mg receiving participants in the pooled DEPICT populations. CONCLUSIONS: Compared with the pooled DEPICT population, the benefit/risk profile of adjunct dapagliflozin therapy was more favourable in individuals with type 1 diabetes with body mass index ≥27 kg/m2 because of the reduced risk of diabetic ketoacidosis in this population.

Pharmacokinetics and pharmacodynamics of dapagliflozin in combination with insulin in Japanese patients with type 1 diabetes.

AIMS: To assess the pharmacokinetics/pharmacodynamics (PK/PD) of dapagliflozin, a sodium-glucose co-transporter 2 inhibitor that increases urinary glucose excretion (UGE) and its major metabolite, dapagliflozin-3-O-glucuronide (D3OG), in Japanese patients with type 1 diabetes (T1D) and inadequate glycaemic control (HbA1c 7%-10%). MATERIALS AND METHODS: Japanese patients (18-65 years) with inadequately controlled T1D were randomized 1:1:1 to dapagliflozin 5 mg, 10 mg or placebo (n = 14 each) once daily for 7 days, with adjustable insulin. The PK/PD characteristics of dapagliflozin and D3OG were assessed on Day 7. Patients underwent follow-up evaluation on Days 8 and 14. Adverse events (AEs), hypoglycaemic episodes and events of diabetic ketoacidosis (DKA) were recorded over the treatment and follow-up periods. RESULTS: A total of 42 randomized patients received dapagliflozin or placebo. PK variables increased in a dose-dependent manner. D3OG was generated rapidly, with a median time to maximum plasma concentration of 2.0 hours (1.0-3.0). The dapagliflozin dose-UGE relationship was attenuated, with larger insulin dose reductions than anticipated. Mean percent (standard error) changes in total daily insulin dose from baseline to Day 7 were - 36.86% (3.32), -39.13% (2.68) and - 4.97% (5.28) for dapagliflozin 5 mg and 10 mg and for placebo, respectively. No DKA was reported. AEs were consistent with the established dapagliflozin safety profile. There was no increase in hypoglycaemia. CONCLUSIONS: The PK and safety profiles of dapagliflozin in Japanese patients with T1D were consistent with previous studies, but with an unanticipated attenuation of the PD dose-response measured as UGE.

CT colonography: implementation, indications, and technical performance - a follow-up national survey.

BACKGROUND: Computed tomography colonography (CTC) is an accepted complement or alternative to optical colonoscopy (OC) but its implementation is incompletely analyzed, and technical performance varies between centers. PURPOSE: To evaluate implementation, indications, and technical performance of CTC in Sweden and to evaluate compliance to international guidelines. MATERIAL AND METHODS: A structured, self-assessed questionnaire regarding implementation and technical performance of CTC was sent to all eligible radiology departments in Sweden. Eighty-six out of 89 departments replied. Comparisons were made with similar national surveys from 2004 and 2009. RESULTS: The number of centers performing CTC gradually increased from 23 in 2004 to 77 in 2016. In parallel, centers performing barium enema (BE) examinations have decreased from 89 in 2004 to 13 in 2016. Main reasons stated for still performing BE were lack of resources regarding CTC/OC. Main reasons for not performing CTC were lack of suitable software, lack of machine/reading time, and lack of experience. The majority of centers follow international CTC guidelines. An important exception is fecal tagging, which was implemented in only 63% of the centers. Incomplete OC remains a major indication for CTC, while preoperative CTC in colorectal cancer and follow-up after diverticulitis have emerged as new indications. CONCLUSION: CTC today is well implemented in routine healthcare but still lacking in capacity. Indications have expanded over time, and most departments perform "state of the art" CTC, although fecal tagging is incompletely implemented.

Role of regulatory T cells in acute myeloid leukemia patients undergoing relapse-preventive immunotherapy.

Regulatory T cells (Tregs) have been proposed to dampen functions of anti-neoplastic immune cells and thus promote cancer progression. In a phase IV trial (Re:Mission Trial, NCT01347996, http://www.clinicaltrials.gov ) 84 patients (age 18-79) with acute myeloid leukemia (AML) in first complete remission (CR) received ten consecutive 3-week cycles of immunotherapy with histamine dihydrochloride (HDC) and low-dose interleukin-2 (IL-2) to prevent relapse of leukemia in the post-consolidation phase. This study aimed at defining the features, function and dynamics of Foxp3+CD25highCD4+ Tregs during immunotherapy and to determine the potential impact of Tregs on relapse risk and survival. We observed a pronounced increase in Treg counts in peripheral blood during initial cycles of HDC/IL-2. The accumulating Tregs resembled thymic-derived natural Tregs (nTregs), showed augmented expression of CTLA-4 and suppressed the cell cycle proliferation of conventional T cells ex vivo. Relapse of AML was not prognosticated by Treg counts at onset of treatment or after the first cycle of immunotherapy. However, the magnitude of Treg induction was diminished in subsequent treatment cycles. Exploratory analyses implied that a reduced expansion of Tregs in later treatment cycles and a short Treg telomere length were significantly associated with a favorable clinical outcome. Our results suggest that immunotherapy with HDC/IL-2 in AML entails induction of immunosuppressive Tregs that may be targeted for improved anti-leukemic efficiency.

TLR-Stimulated Neutrophils Instruct NK Cells To Trigger Dendritic Cell Maturation and Promote Adaptive T Cell Responses.

Polymorphonuclear neutrophils (PMNs) are innate effector cells with pivotal roles in pathogen recognition, phagocytosis, and eradication. However, their role in the development of subsequent immune responses is incompletely understood. This study aimed to identify mechanisms of relevance to the cross talk between human neutrophils and NK cells and its potential role in promoting adaptive immunity. TLR-stimulated PMNs were found to release soluble mediators to attract and activate NK cells in vitro. PMN-conditioned NK cells displayed enhanced cytotoxicity and cytokine production, and responded vigorously to ensuing stimulation with exogenous and endogenous IL-12. The neutrophil-induced activation of NK cells was prevented by caspase-1 inhibitors and by natural antagonists to IL-1 and IL-18, suggesting a role for the NOD-like receptor family pyrin domain containing-3 inflammasome. In addition, PMN-conditioned NK cells triggered the maturation of monocyte-derived dendritic cells, which promoted T cell proliferation and IFN-γ production. These data imply that neutrophils attract NK cells to sites of infection to convert these cells into an active state, which drives adaptive immune responses via maturation of dendritic cells. Our results add to a growing body of evidence that suggests a sophisticated role for neutrophils in orchestrating the immune response to pathogens.

Histamine promotes the development of monocyte-derived dendritic cells and reduces tumor growth by targeting the myeloid NADPH oxidase.

The efficiency of immune-mediated clearance of cancer cells is hampered by immunosuppressive mediators in the malignant microenvironment, including NADPH oxidase-derived reactive oxygen species. We aimed at defining the effects of histamine, an inhibitor of the myeloid NADPH oxidase/NOX2, on the development of Ag-presenting dendritic cells (DCs) from myeloid precursors and the impact of these mechanisms for tumor growth. Histamine was found to promote the maturation of human DCs from monocytes by increasing the expression of HLA-DR and costimulatory molecules, which resulted in improved induction of Th cells with Th0 polarity. Experiments using wild-type and NOX2-deficient myelomonoblastic cells showed that histamine facilitated myeloid cell maturation only in cells capable of generating reactive oxygen species. Treatment of mice with histamine reduced the growth of murine EL-4 lymphomas in parallel with an increment of tumor-infiltrating DCs in NOX2-sufficient mice but not in NOX2-deficient (gp91(phox) (-/-)) mice. We propose that strategies to target the myeloid NADPH oxidase may facilitate the development of endogenous DCs in cancer.

Monocytic AML cells inactivate antileukemic lymphocytes: role of NADPH oxidase/gp91(phox) expression and the PARP-1/PAR pathway of apoptosis.

Dysfunction of T cells and natural killer (NK) cells has been proposed to determine the course of disease in acute myeloid leukemia (AML), but only limited information is available on the mechanisms of lymphocyte inhibition. We aimed to evaluate to what extent human malignant AML cells use NADPH oxidase-derived reactive oxygen species (ROS) as an immune evasion strategy. We report that a subset of malignant myelomonocytic and monocytic AML cells (French-American-British [FAB] classes M4 and M5, respectively), recovered from blood or BM of untreated AML patients at diagnosis, expressed the NADPH oxidase component gp91(phox). Highly purified FAB M4/M5 AML cells produced large amounts of ROS on activation and triggered poly-[ADP-ribose] polymerase-1-dependent apoptosis in adjacent NK cells, CD4(+) T cells, and CD8(+) T cells. In contrast, immature (FAB class M1) and myeloblastic (FAB class M2) AML cells rarely expressed gp91(phox), did not produce ROS, and did not trigger NK or T-cell apoptosis. Microarray data from 207 AML patients confirmed a greater expression of gp91(phox) mRNA by FAB-M4/M5 AML cells than FAB-M1 cells (P < 10(-11)) or FAB-M2 cells (P < 10(-9)). Our data are suggestive of a novel mechanism by which monocytic AML cells evade cell-mediated immunity.

Human NK Cells induce neutrophil apoptosis via an NKp46- and Fas-dependent mechanism.

Polymorphonuclear neutrophils (PMN) are potent inflammatory effector cells essential to host defense, but at the same time they may cause significant tissue damage. Thus, timely induction of neutrophil apoptosis is crucial to avoid tissue damage and induce resolution of inflammation. NK cells have been reported to influence innate and adaptive immune responses by multiple mechanisms including cytotoxicity against other immune cells. In this study, we analyzed the effect of the interaction between NK cells and neutrophils. Coculture experiments revealed that human NK cells could trigger caspase-dependent neutrophil apoptosis in vitro. This event was dependent on cell-cell contact, and experiments using blocking Abs indicated that the effect was mediated by the activating NK cell receptor NKp46 and the Fas pathway. CD56-depleted lymphocytes had minimal effects on neutrophil survival, suggesting that the ability to induce neutrophil apoptosis is specific to NK cells. Our findings provide evidence that NK cells may accelerate neutrophil apoptosis, and that this interaction may be involved in the resolution of acute inflammation.

All-photonic kinase inhibitors: light-controlled release-and-report inhibition.

Light-responsive molecular tools targeting kinases affords one the opportunity to study the underlying cellular function of selected kinases. In efforts to externally control lymphocyte-specific protein tyrosine kinase (LCK) activity, the development of release-and-report LCK inhibitors is described, in which (i) the release of the active kinase inhibitor can be controlled externally with light; and (ii) fluorescence is employed to report both the release and binding of the active kinase inhibitor. This introduces an unprecedented all-photonic method for users to both control and monitor real-time inhibitory activity. A functional cellular assay demonstrated light-mediated LCK inhibition in natural killer cells. The use of coumarin-derived caging groups resulted in rapid cellular uptake and non-specific intracellular localisation, while a BODIPY-derived caging group predominately localised in the cellular membrane. This concept of release-and-report inhibitors has the potential to be extended to other biorelevant targets where both spatiotemporal control in a cellular setting and a reporting mechanism would be beneficial.