High accuracy barrier heights, enthalpies, and rate coefficients for chemical reactions

Quantitative chemical reaction data, including activation energies and reaction rates, are crucial for developing detailed kinetic mechanisms and accurately predicting reaction outcomes. However, such data are often difficult to find, and high-quality datasets are especially rare. Here, we use CCSD(T)-F12a/cc-pVDZ-F12//ωB97X-D3/def2-TZVP to obtain high-quality single point calculations for nearly 22,000 unique stable species and transition states. We report the results from these quantum chemistry calculations and extract the barrier heights and reaction enthalpies to create a kinetics dataset of nearly 12,000 gas-phase reactions. These reactions involve H, C, N, and O, contain up to seven heavy atoms, and have cleaned atom-mapped SMILES. Our higher-accuracy coupled-cluster barrier heights differ significantly (RMSE of ∼5 kcal mol⁻¹) relative to those calculated at ωB97X-D3/def2-TZVP. We also report accurate transition state theory rate coefficients \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${k}_{\infty }(T)$$\end{document}k∞(T) between 300 K and 2000 K and the corresponding Arrhenius parameters for a subset of rigid reactions. We believe this data will accelerate development of automated and reliable methods for quantitative reaction prediction.

Measurement(s)	Barrier Heights • Enthalpies • Rate Coefficients
Technology Type(s)	ab initio quantum chemistry computational method

Biomimetic Nanoemulsions for Oxygen Delivery In Vivo

Blood transfusion is oftentimes required for patients suffering from acute trauma or undergoing surgical procedures in order to help maintain the body's oxygen levels. The continued demand worldwide for blood products is expected to put significant strain on available resources and infrastructure. Unfortunately, efforts to develop viable alternatives to human red blood cells for transfusion are generally unsuccessful. Here, a hybrid natural-synthetic nanodelivery platform that combines the biocompatibility of the natural RBC membrane with the oxygen-carrying ability of perfluorocarbons is reported. The resulting formulation can be stored long-term and exhibits a high capacity for oxygen delivery, helping to mitigate the effects of hypoxia in vitro. In an animal model of hemorrhagic shock, mice are resuscitated at an efficacy comparable to whole blood infusion. By leveraging the advantageous properties of its constituent parts, this biomimetic oxygen delivery system may have the potential to address a critical need in the clinic.

Coating nanoparticles with gastric epithelial cell membrane for targeted antibiotic delivery against Helicobacter pylori infection

Inspired by the natural pathogen-host interactions and adhesion, this study reports on the development of a novel targeted nanotherapeutics for the treatment of Helicobacter pylori (H. pylori) infection. Specifically, plasma membranes of gastric epithelial cells (e.g. AGS cells) are collected and coated onto antibiotic-loaded polymeric cores, the resulting biomimetic nanoparticles (denoted AGS-NPs) bear the same surface antigens as the source AGS cells and thus have inherent adhesion to H. pylori bacteria. When incubated with H. pylori bacteria in vitro, the AGS-NPs preferentially accumulate on the bacterial surfaces. Using clarithromycin (CLR) as a model antibiotic and a mouse model of H. pylori infection, the CLR-loaded AGS-NPs demonstrate superior therapeutic efficacy as compared the free drug counterpart as well as non-targeted nanoparticle control group. Overall, this work illustrates the promise and strength of using natural host cell membranes to functionalize drug nanocarriers for targeted drug delivery to pathogens that colonize on the host cells. As host-pathogen adhesion represents a common biological event for various types of pathogenic bacteria, the bioinspired nanotherapeutic strategy reported here represents a versatile delivery platform that may be applied to treat numerous infectious diseases.

Tyrosine kinase inhibition increases the cell surface localization of FLT3-ITD and enhances FLT3-directed immunotherapy of acute myeloid leukemia

The fms-related tyrosine kinase 3 (FLT3) receptor has been extensively studied over the past two decades with regard to oncogenic alterations that do not only serve as prognostic markers but also as therapeutic targets in acute myeloid leukemia (AML). Internal tandem duplications (ITDs) became of special interest in this setting as they are associated with unfavorable prognosis. Because of sequence-dependent protein conformational changes FLT3-ITD tends to autophosphorylate and displays a constitutive intracellular localization. Here, we analyzed the effect of tyrosine kinase inhibitors (TKIs) on the localization of the FLT3 receptor and its mutants. TKI treatment increased the surface expression through upregulation of FLT3 and glycosylation of FLT3-ITD and FLT3-D835Y mutants. In T cell-mediated cytotoxicity (TCMC) assays, using a bispecific FLT3 × CD3 antibody construct, the combination with TKI treatment increased TCMC in the FLT3-ITD-positive AML cell lines MOLM-13 and MV4-11, patient-derived xenograft cells and primary patient samples. Our findings provide the basis for rational combination of TKI and FLT3-directed immunotherapy with potential benefit for FLT3-ITD-positive AML patients.

Persistence of pre-leukemic clones during first remission and risk of relapse in acute myeloid leukemia

Some patients with acute myeloid leukemia (AML) who are in complete remission after induction chemotherapy harbor persisting pre-leukemic clones, carrying a subset of leukemia-associated somatic mutations. There is conflicting evidence on the prognostic relevance of these clones for AML relapse. Here, we characterized paired pre-treatment and remission samples from 126 AML patients for mutations in 68 leukemia-associated genes. Fifty patients (40%) retained ⩾1 mutation during remission at a variant allele frequency of ⩾2%. Mutation persistence was most frequent in DNMT3A (65% of patients with mutations at diagnosis), SRSF2 (64%), TET2 (55%), and ASXL1 (46%), and significantly associated with older age (P<0.0001) and, in multivariate analyses adjusting for age, genetic risk, and allogeneic transplantation, with inferior relapse-free survival (hazard ratio, 2.34; P=0039) and overall survival (hazard ratio, 2.14; P=036). Patients with persisting mutations had a higher cumulative incidence of relapse before, but not after allogeneic stem cell transplantation. Our work underlines the relevance of mutation persistence during first remission as a novel risk factor in AML. Persistence of pre-leukemic clones may contribute to the inferior outcome of elderly AML patients. Allogeneic transplantation abrogated the increased relapse risk associated with persisting pre-leukemic clones, suggesting that mutation persistence may guide postremission treatment.Leukemia accepted article preview online, 18 December 2017. doi:10.1038/leu.2017.350.

Assessment of imatinib as first-line treatment of chronic myeloid leukemia: 10-year survival results of the randomized CML study IV and impact of non-CML determinants

Chronic myeloid leukemia (CML)-study IV was designed to explore whether treatment with imatinib (IM) at 400 mg/day (n=400) could be optimized by doubling the dose (n=420), adding interferon (IFN) (n=430) or cytarabine (n=158) or using IM after IFN-failure (n=128). From July 2002 to March 2012, 1551 newly diagnosed patients in chronic phase were randomized into a 5-arm study. The study was powered to detect a survival difference of 5% at 5 years. After a median observation time of 9.5 years, 10-year overall survival was 82%, 10-year progression-free survival was 80% and 10-year relative survival was 92%. Survival between IM400 mg and any experimental arm was not different. In a multivariate analysis, risk group, major-route chromosomal aberrations, comorbidities, smoking and treatment center (academic vs other) influenced survival significantly, but not any form of treatment optimization. Patients reaching the molecular response milestones at 3, 6 and 12 months had a significant survival advantage. For responders, monotherapy with IM400 mg provides a close to normal life expectancy independent of the time to response. Survival is more determined by patients' and disease factors than by initial treatment selection. Although improvements are also needed for refractory disease, more life-time can currently be gained by carefully addressing non-CML determinants of survival.

Silencing of GATA3 defines a novel stem cell-like subgroup of ETP-ALL

Background

GATA3 is pivotal for the development of T lymphocytes. While its effects in later stages of T cell differentiation are well recognized, the role of GATA3 in the generation of early T cell precursors (ETP) has only recently been explored. As aberrant GATA3 mRNA expression has been linked to cancerogenesis, we investigated the role of GATA3 in early T cell precursor acute lymphoblastic leukemia (ETP-ALL).

Methods

We analyzed GATA3 mRNA expression by RT-PCR (n = 182) in adult patients with T-ALL. Of these, we identified 70 of 182 patients with ETP-ALL by immunophenotyping. DNA methylation was assessed genome wide (Illumina Infinium® HumanMethylation450 BeadChip platform) in 12 patients and GATA3-specifically by pyrosequencing in 70 patients with ETP-ALL. The mutational landscape of ETP-ALL with respect to GATA3 expression was investigated in 18 patients and validated by Sanger sequencing in 65 patients with ETP-ALL. Gene expression profiles (Affymetrix Human genome U133 Plus 2.0) of an independent cohort of adult T-ALL (n = 83) were used to identify ETP-ALL and investigate GATA3^low and GATA3^high expressing T-ALL patients. In addition, the ETP-ALL cell line PER-117 was investigated for cytotoxicity, apoptosis, GATA3 mRNA expression, DNA methylation, and global gene expression before and after treatment with decitabine.

Results

In our cohort of 70 ETP-ALL patients, 33 % (23/70) lacked GATA3 expression and were thus defined as GATA3^low. DNA methylation analysis revealed a high degree of GATA3 CpG island methylation in GATA3^low compared with GATA3^high ETP-ALL patients (mean 46 vs. 21 %, p < 0.0001). Genome-wide expression profiling of GATA3^low ETP-ALL exhibited enrichment of myeloid/lymphoid progenitor (MLP) and granulocyte/monocyte progenitor (GMP) genes, while T cell-specific signatures were downregulated compared to GATA3^high ETP-ALL. Among others, FLT3 expression was upregulated and mutational analyses demonstrated a high rate (79 %) of FLT3 mutations. Hypomethylating agents induced reversal of GATA3 silencing, and gene expression profiling revealed downregulation of hematopoietic stem cell genes and upregulation of T cell differentiation.

Conclusions

We propose GATA3^low ETP-ALL as a novel stem cell-like leukemia with implications for the use of myeloid-derived therapies.

Electronic supplementary material

The online version of this article (doi:10.1186/s13045-016-0324-8) contains supplementary material, which is available to authorized users.

The target cell of transformation is distinct from the leukemia stem cell in murine CALM/AF10 leukemia models

The CALM/AF10 fusion gene is found in various hematological malignancies including acute myeloid leukemia (AML), T-cell acute lymphoblastic leukemia and malignant lymphoma. We have previously identified the leukemia stem cell (LSC) in a CALM/AF10-driven murine bone marrow transplant AML model as B220+ lymphoid cells with B-cell characteristics. To identify the target cell for leukemic transformation or 'cell of origin of leukemia' (COL) in non-disturbed steady-state hematopoiesis, we inserted the CALM/AF10 fusion gene preceded by a loxP-flanked transcriptional stop cassette into the Rosa26 locus. Vav-Cre-induced panhematopoietic expression of the CALM/AF10 fusion gene led to acute leukemia with a median latency of 12 months. Mice expressing CALM/AF10 in the B-lymphoid compartment using Mb1-Cre or CD19-Cre inducer lines did not develop leukemia. Leukemias had a predominantly myeloid phenotype but showed coexpression of the B-cell marker B220, and had clonal B-cell receptor rearrangements. Using whole-exome sequencing, we identified an average of two to three additional mutations per leukemia, including activating mutations in known oncogenes such as FLT3 and PTPN11. Our results show that the COL for CALM/AF10 leukemia is a stem or early progenitor cell and not a cell of B-cell lineage with a phenotype similar to that of the LSC in CALM/AF10+ leukemia.

Blockade of the PD-1/PD-L1 axis augments lysis of AML cells by the CD33/CD3 BiTE antibody construct AMG 330: reversing a T-cell-induced immune escape mechanism

Bispecific T-cell engagers (BiTEs) are very effective in recruiting and activating T cells. We tested the cytotoxicity of the CD33/CD3 BiTE antibody construct AMG 330 on primary acute myeloid leukemia (AML) cells ex vivo and characterized parameters contributing to antileukemic cytolytic activity. The E:T ratio and the CD33 expression level significantly influenced lysis kinetics in long-term cultures of primary AML cells (n=38). AMG 330 induced T-cell-mediated proinflammatory conditions, favoring the upregulation of immune checkpoints on target and effector cells. Although not constitutively expressed at the time of primary diagnosis (n=123), PD-L1 was strongly upregulated on primary AML cells upon AMG 330 addition to ex vivo cultures (n=27, P<0.0001). This phenomenon was cytokine-driven as the sole addition of interferon (IFN)-γ and tumor necrosis factor-α also induced expression. Through blockade of the PD-1/PD-L1 interaction, AMG 330-mediated lysis (n=9, P=0.03), T-cell proliferation (n=9, P=0.01) and IFN-γ secretion (n=8, P=0.008) were significantly enhanced. The combinatorial approach was most beneficial in settings of protracted AML cell lysis. Taken together, we have characterized a critical resistance mechanism employed by primary AML cells under AMG 330-mediated proinflammatory conditions. Our results support the evaluation of checkpoint molecules in upcoming clinical trials with AMG 330 to enhance BiTE antibody construct-mediated cytotoxicity.

Early molecular and cytogenetic response is predictive for long-term progression-free and overall survival in chronic myeloid leukemia (CML)

In the face of competing first-line treatment options for CML, early prediction of prognosis on imatinib is desirable to assure favorable survival or otherwise consider the use of a second-generation tyrosine kinase inhibitor (TKI). A total of 1303 newly diagnosed imatinib-treated patients (pts) were investigated to correlate molecular and cytogenetic response at 3 and 6 months with progression-free and overall survival (PFS, OS). The persistence of BCR-ABL transcript levels >10% according to the international scale (BCR-ABL(IS)) at 3 months separated a high-risk group (28% of pts; 5-year OS: 87%) from a group with >1-10% BCR-ABL(IS) (41% of pts; 5-year OS: 94%; P=0.012) and from a group with ≤1% BCR-ABL(IS) (31% of pts; 5-year OS: 97%; P=0.004). Cytogenetics identified high-risk pts by >35% Philadelphia chromosome-positive metaphases (Ph+, 27% of pts; 5-year OS: 87%) compared with ≤35% Ph+ (73% of pts; 5-year OS: 95%; P=0.036). At 6 months, >1% BCR-ABL(IS) (37% of pts; 5-year OS: 89%) was associated with inferior survival compared with ≤1% (63% of pts; 5-year OS: 97%; P<0.001) and correspondingly >0% Ph+ (34% of pts; 5-year OS: 91%) compared with 0% Ph+ (66% of pts; 5-year OS: 97%; P=0.015). Treatment optimization is recommended for pts missing these landmarks.

[Severe microcytic anemia with megaloblastic changes in the bone marrow. A hematological paradoxon?]

We discuss the case of a 32 year-old male with severe microcytic anemia (hemoglobin 2,9 g/dl) and megaloblastic changes in the bone marrow. The patient reported of substantial dietary weight loss. The family history was positive for beta-thalassemia. Previous blood work showed iron deficiency with mild anemia. Further work-up verified beta-thalassemia minor and revealed severely decreased vitamin B12 levels with positive anti intrinsic-factor antibodies, pathognomonic for autoimmune pernicious anemia. The paradoxon therefore dissolved as a pernicious anemia with megaloblastic changes with microcytic erythrocytes due to beta-thalassemia.

[Modern leukemia diagnosis in adults]

Identification of numerous criteria important in the pathogenesis, biology, prognosis and treatment of the different types of leukemia necessitates a broad spectrum of diagnostic methods for the initial diagnosis and in the further course of the disease. In addition to cytomorphology with cytochemistry, which is been path-breaking for the application of further diagnostic methods, cytogenetics has become an obligatory diagnostic tool. Immunophenotyping and, even more relevant, molecular genetics plays an important role. Other diagnostic techniques are widely developed. The diagnostic procedures are described, with a focus on their mode of operation as well as their clinical significance. Because of their high clinical relevance and growing complexity, the diagnosis of leukemias should be performed in specialized laboratories.

BH3 mimetic ABT-737 neutralizes resistance to FLT3 inhibitor treatment mediated by FLT3-independent expression of BCL2 in primary AML blasts

FLT3 defines a promising target for the treatment of acute myeloid leukemia (AML). In contrast to their efficacy in cell lines, FLT3-specific inhibitors as single agents have only modest clinical activity in patients with AML. As demonstrated here, overexpression of anti-apoptotic proteins of the BCL2 family leads to resistance against FLT3 inhibitors in a hematopoietic cell line model with activating FLT3 mutations. The susceptibility to FLT3 inhibition could be restored by treatment with the novel BH3 mimetic ABT-737. Primary AML samples tested in our study showed a high expression of BCL2 protein, but not of BCL-xL or MCL1. BCL2 protein levels were not reduced after dephosphorylation of FLT3 and its downstream target STAT5 in patient samples with FLT3 internal tandem duplications. Interestingly, treatment with ABT-737 caused apoptotic cell death in all primary AML samples at submicromolar level and synergized efficiently with FLT3 inhibition in AML samples with activating FLT3 mutations. In contrast to AML cell lines, BCR-ABL transformed human cells showed resistance to ABT-737, which might be due to the induction of MCL1 by BCR-ABL. Inhibition of BCL2 family members might define a novel highly efficient and specific strategy in the combined or monotreatment of AML.

[Nonsymptomatic leukocytosis]

Leukocytosis is a condition often met with in the clinical and ambulatory setting. Although it is usually caused by an increase in the numbers of neutrophilic granulocytes, an increase in other leukocytes populations may also account for leukocytosis. Etiologically, both primary pathological conditions affecting the white blood cells, such as various forms of leukemia and lymphomas, and also rare genetic disorders must be considered. Decidedly more common, however, are reactive changes caused by infections, cigarette smoking, chronic inflammation, necrotic tissue or certain drugs. Although moderate leukocytosis in the absence of a clinical correlate and/or an apparent trigger, requires no diagnostic clarification, it should be kept under observation. If the etiology is uncertain, or a treatment-requiring disorder is suspected, the differential blood count is at the focus of the further diagnostic work-up. Depending upon the findings, this is supplemented by additional laboratory parameters, bone marrow examination, microbiological investigations and imaging procedures. Leukostasis resulting from vasoocclusion in the presence of very high numbers of leukocytes represents an emergency situation, and is an indication for leukapheresis.

[Fortuitous finding: thrombocytopenia and thrombocytosis]

Thrombocytopenia is present when the number of platelets drops to below 150 G/l. Leaving aside pseudothrombocytopenia, such a situation may be triggered by pregnancy or a range of different drugs, or may signify the presence of idiopathic thrombocytopenic purpura (ITP). Thrombocytosis is present when the platelet count exceeds 500 G/l. This condition includes a large variety of forms of reactive thrombocytosis, a clonal increase in thrombocytes in hematological diseases, and the rare condition of familial thrombocytosis.

[Elevated Hemoglobin--polyglobulia or polycythemia?]

An increase in Hb levels, haematocrit or the absolute number of red blood cells may be evidence of polycythemia rubra vera. Much more commonly, however, erythrocytosis is due to an underlying non-hematological disease. To establish the diagnosis of polycythemia, a secondary polyglobulia must first be excluded. If no evidence of polyglobulia is found, or if EPO levels are decreased, or splenomegaly not accountable for by portal hypertension is present, a specific diagnostic work-up must be performed by a hematologist/oncologist. This includes a bone marrow aspiration, cytological examination and molecular genetic testing.

Risikoadaptierte Therapie der akuten myeloischen Leukämie

Genetic and molecular techniques have provided increasing insights into the biology of acute myeloid leukemia (AML). These investigations showed that AML is not a homogeneous disease but a heterogeneous group of biologically different subentities. These subentities are currently primarily defined by cytogenetics and molecular markers. They differ substantially in response to therapy and long-term outcome and hence allow different risk groups of patients to be defined. These will guide therapeutic decisions in future therapeutic strategies and may ultimately lead to an individualized treatment concept.

Towards a pathogenesis-oriented therapy of acute myeloid leukemia

Genetic and molecular techniques have provided increasing insights into the biology of acute myeloid leukemia (AML). These investigations showed that AML is not a homogeneous disease but a heterogeneous group of biologically different subentities. These subentities are currently primarily defined by cytogenetics by which three main subgroups can be discriminated: AML with balanced translocations, AML with unbalanced aberrations and AML without cytogenetically detectable aberrations. Within the latter group molecular alterations are identified in more than half of cases such as NPM mutations, FLT3 mutations, MLL duplications and mutations of CEBP-alpha. The clinical meaning of these findings is illustrated by substantial differences in response to therapy and long-term outcome. As demonstrated by the recent multicenter trial of the German AML Cooperative Group (AMLCG) and other studies intensification of induction therapy may improve the results in distinct subtypes but fails to do so in others. Therefore, new strategies need to be explored which incorporate the knowledge about the biology of AML to develop biology adapted treatment strategies. This process has just begun and is predominantly determined by the availability of new agents and their evaluation in clinical phase I and II studies. A variety of targets are currently explored and some trials have yielded promising results already. The step towards a biology adapted treatment of AML is long and requires the combined efforts of researchers, clinicians and the pharmaceutical industry. The first steps towards this goal have been taken and give rise to the hope for more effective and more specific therapies of AML.

Molekulare Zielstrukturen in der Onkologie

Substantial progress has been made in recent years in understanding the molecular pathogenesis of malignant disorders, especially in identification of molecular targets for therapeutic interventions ("targeted therapies"). An important group of therapeutical targets are signaling cascades, e.g. protein tyrosine kinases (PTK) that are activated by mutations, translocations or overexpression. Small molecule inhibitors that compete with ATP and inhibit kinase activity have produced clinical impressive responses in chronic myeloid leukemia, gastrointestinal stroma tumors and non-small cell lung cancer. Another group of cellular targets is represented by tumor-selective cell surface proteins that can serve as target structures for antibodies. Therapeutical concepts using monoclonal antibodies have substantially improved response rates in patients with malignant lymphomas and are currently evaluated in other types of cancer. The definition of molecular target structures critical for the malignant phenotype is driving a new era of integrated diagnostics and therapeutics in the field of oncology.

Constitutive activation of STAT transcription factors in acute myelogenous leukemia

Hematopoietic growth factors (HGF) are essential for proliferation and differentiation of hematopoietic precursors and activate a distinct set of JAK-STAT (Janus kinases-signal transducers and activators of transcription) proteins. Previous results from our group have shown a strong expression of JAK-STAT proteins in primary acute myelogenous leukemia (AML) blasts and AML cell lines. Here, we asked whether a constitutive activation of the JAK-STAT pathway might be involved in the pathogenesis of AML. We could demonstrate a constitutive activation of STAT1, 3 and 5 by immunoprecipitation of the tyrosine phosphorylated proteins in different human AML cell lines. Three patterns of STAT activation were found: (I) activation of only STAT1, (II) activation of STAT1 in combination with STAT3, and (III) activation of STAT1, 3 and 5. Furthermore, STAT1 and 3 formed stable heterodimers only in cell lines with constitutive STAT3 activation. In all cell lines analyzed, tyrosine phosphorylation of the four known Janus kinases could not be detected, although JAK1 was stably associated with STAT3. To further analyze whether a constitutive activation of tyrosine kinases might contribute to the autonomous growth of AML blasts, inhibitor studies were performed. The tyrphostin AG490, an inhibitor of the JAK-STAT pathway, but not A1, an inactive tyrphostin induced a time- and dose-dependent growth arrest without overt morphological signs of differentiation in AML cell lines. Our results show that STAT transcription factors are constitutively activated in human AML cell lines and might contribute to the autonomous proliferation of AML blasts. Inhibition of this pathway might be of interest for the establishment of more specific antileukemic strategies.

Expression of granulocyte colony-stimulating factor- and granulocyte-macrophage colony-stimulating factor-associated signal transduction proteins of the JAK/STAT pathway in normal granulopoiesis and in blast cells of acute myelogenous leukemia

Acute myelogenous leukemia (AML) is characterized by the malignant transformation of hematopoietic stem cells leading to dysregulated growth and differentiation of myeloid cells. Normally, proliferation and differentiation of myeloid cells are regulated by cytokines such as granulocyte colony-stimulating factor (G-CSF) or granulocyte-macrophage colony-stimulating factor (GM-CSF). Abnormal signaling of the signal transduction pathway from the cytokine receptors via Janus kinases (JAKs) and signal transducers and activators of transcription (STATs) might be involved in the pathogenesis of AML. We examined whether an abnormal expression of one of the four JAKs, STAT1, STAT3, STAT5, or the tyrosine phosphatase SHP-1, a negative regulator of this pathway, is associated with malignant transformation in AML. Analysis of the expression of proteins of the JAK/STAT pathway in normal myeloid cells at three stages of maturation revealed a strong expression of all proteins in CD34+ cells, whereas the level of the proteins was significantly lower in granulocytic precursors and mature neutrophils. Furthermore, during maturation the relation of the isoforms of STAT1 and STAT3 changed from predominantly alpha to predominantly beta. Leukemic blast cells from 25 patients and 12 cell lines showed a high level of STAT proteins and SHP-1, whereas a deficiency of at least one of the four JAKs was found in 10 of 25 patients. In primary AML blast cells a deficiency of three JAKs was more common in patients with an abnormal karyotype. In addition, a lack of JAK2 and Tyk2 protein was strongly associated with the FAB M2 phenotype. The proliferation rate in response to GM-CSF available in a small number of patients appears to be related to the JAK2 expression. Our data suggest that the degree of expression of G-CSF/GM-CSF receptor-associated proteins of the JAK/STAT pathway in normal myeloid cells is related with their clonogenic potential. STAT3 appears to be involved in early differentiation. Similar to CD34+ cells, it is likely that the high levels of STATs and SHP-1 found in leukemic cells reflects their proliferative activity, whereas a lack of members of the JAK family might lead to an inability to proliferate in response to G-CSF/GM-CSF described in a considerable percentage of AML blasts.

Combination chemotherapy with CHOP for recurrent thrombotic thrombocytopenic purpura

We report the case of a 42-year-old woman with chronic recurrent thrombotic thrombocytopenic purpura. Therapy with corticosteroids, high-dose immunoglobulins, plasma exchange and cyclophosphamide only induced short-lasting remissions during a course of almost 3 months. Following a severe relapse on day 90 after the start of symptoms, polychemotherapy with cyclophosphamide. adriamycin, vincristine and prednisolone (CHOP) was begun. After two cycles of CHOP the patient has stayed in complete remission, with normal platelet counts for more than 9 months to date.

Functional features of neutrophils induced by G-CSF and GM-CSF treatment: differential effects and clinical implications

G-CSF and GM-CSF are hematopoietic growth factors required for proliferation and differentiation of hematopoietic precursors. G-CSF is now widely used to overcome neutropenias of various origins. Beside the absolute number, the functional capacity of neutrophils at sites of inflammation is of major importance in host defense. This review summarizes major functional and phenotypical features of neutrophils induced by G-CSF treatment in patients with acquired and congenital neutropenias. Furthermore, we focus on the differential effect of G-CSF and GM-CSF on neutrophil function in vitro and in vivo. Some of the altered abilities of cytokine-induced neutrophils are important to understand side-effects of G-CSF therapy.

Surface and mRNA expression of the CD52 antigen by human eosinophils but not by neutrophils

Eosinophilic and neutrophilic granulocytes represent major effector cells in the inflammatory response. Whereas neutrophils are predominantly involved in bacterial infections, eosinophils are of essential importance in the allergic inflammation. Surface markers have been used to distinguish neutrophils (CD16+) from eosinophils (CD16-) and might indicate different functional properties of these cells. In this study, expression and functional activity of CD52 on human eosinophils and neutrophils was investigated in nonatopic healthy donors and from patients with hypereosinophilia. Flow cytometric analysis using different anti-CD52 monoclonal antibodies (MoAbs) (mouse IgG3, humanized IgG1, and rat IgM) showed significant and homogeneous expression of CD52 on human eosinophils, but not on neutrophils. In addition, reverse transcription-polymerase chain reaction and Northern blot analysis showed that CD52 mRNA was constitutively expressed in eosinophils but not in neutrophils. Furthermore, expression of CD52 could be diminished in a dose-dependent manner by preincubation of eosinophils with phosphatidylinositol-specific phospholipase C, suggesting that CD52 on eosinophils is anchored to the membrane through a glycosylphosphatidylinositol (GPI) molecule. Whereas the phorbolester phorbol myristate acetate was able to downregulate the expression of CD52 on eosinophils in a dose-dependent manner, different eosinophil activating cytokines and chemotaxins had no effect. Cross-linking of CD52 by mouse anti-CD52 MoAb (IgG3) and humanized anti-CD52 MoAb (IgG1) with goat antimouse antibody and mouse antihuman antibody, respectively, dose-dependently resulted in an inhibition of reactive oxygen species production of eosinophils after stimulation with C5a, platelet-activating factor, and granulocyte-macrophage colony-stimulating factor. In summary, this study shows that the GPI-anchored antigen CD52 is not only a useful marker to distinguish eosinophils from neutrophils. The data point out a novel role of the CD52 antigen on human eosinophils that might be of clinical relevance, because cross-linking of this molecule will stop the destructive power of human eosinophils in the inflammatory tissue.

Identification of the antigen recognized by the monoclonal antibody 31D8

The monoclonal antibody (mAb) 31D8 has previously been described to bind more avidly to functionally active neutrophils and proved to be useful as a differentiation marker of neutrophils. However, attempts to further characterize the antigen recognized by 31D8 have not been successful. Studying the altered Fcgamma-receptor expression of human neutrophils induced by granulocyte colony-stimulating factor (G-CSF) in vivo, we could demonstrate a parallel decrease in the expression of 31D8 and the CD16 antigen. Furthermore, 31D8 showed a binding pattern on leukocyte subsets similar to that of clustered CD16 antibodies, exhibiting identical cells in double-staining experiments. Preincubation of neutrophils with 31D8 resulted in a dose-dependent inhibition of the binding of immune complexes. A decreased expression of the 31D8 antigen was found on the same cell clones to the same extent as found for the 3G8 antigen on neutrophils from patient with paroxysmal nocturnal hemoglobinuria (PNH). Treatment of polymorphonuclear leukocytes (PMN) with PIPLC resulted in a dose-dependent decrease of mAb 31D8 binding, showing that the 31D8 antigen is phosphatidylinositolglycan (PIG)-anchored. Moreover, 31D8 competed with the binding of antibodies (such as mAb 3G8) directed against the binding site of FcgammaRIII for the Fc-part of IgG. However, this mAb did not influence the binding of a CD16 antibody (mAb B73.1) which recognizes an epitope elsewhere on the CD16 antigen. We conclude from our experiments that the mAb 31D8 binds with high avidity to fcgammaRIII (CD16 antigen). Furthermore, our data indicate that its binding site is most probably located at the binding site for the Fc-part of IgG.

Relapse of acute myelogenous leukemia during low dose interleukin-2 (IL-2) therapy. Phenotypic evolution associated with strong expression of the IL-2 receptor alpha chain

BACKGROUND

Interleukin-2 (IL-2) has produced remissions in patients with solid tumors, predominantly malignant melanoma and renal cell carcinoma. Recently, clinical trials have assessed the therapeutic benefit of this cytokine in acute myelogenous leukemia (AML). However, little is known about the potential of IL-2 to promote the growth of leukemic cells in vivo.

METHODS

A patient with acute myelocytic leukemia whose leukemic blasts displayed lymphoid (TdT+ and CD4+) and myeloid features (myeloperoxidase [MPO]+ and CD13+) is reported. The IL-2 receptor alpha chain (CD25 antigen) was present on 28.9% of his blasts. After entering complete remission with chemotherapy, he was treated on a protocol using IL-2 maintenance.

RESULTS

Six weeks after beginning low-dose IL-2, his leukocyte count increased to 448,000/microliters with 86% blasts. The phenotype of these blasts was different from that at diagnosis with expression of the CD25 antigen and the CD33 antigen on 75.9% and 74.8 of the blasts, respectively. Furthermore, 30% of the cells were TdT+, whereas MPO was not detectable.

CONCLUSION

The rapid course of relapse, phenotypic evolution, and the high expression of CD25 antigen on the blasts after IL-2 therapy raise the possibility that the cytokine therapy may have promoted the growth of leukemic cells.

Changes in light-scatter profile, membrane depolarization and calcium mobilization of neutrophils induced by G-CSF in vivo

To extend our studies about phenotypical and functional alterations of G-CSF-induced neutrophils we have evaluated their light-scatter profile, mobilization of intracellular calcium ([Ca2+]i) and membrane depolarization after stimulation. A significant increase in the forward scatter signals could be demonstrated in such neutrophils from patients with neutropenias of various origin and from healthy test subjects. This increase began 4 h and returned to normal 96 h after G-CSF injection in the latter group. We found an impairment of [Ca2+]i mobilization in neutrophils from patients with glycogen storage disease type IB after stimulation of these cells with fMLP. It was even more pronounced than in severe congenital neutropenia (SCN). However, [Ca2+]i fluxes were normal when ionomycin was used. Neutrophils from patients with cyclic neutropenia (cyNP) and chemotherapy-induced neutropenia (chNP) mobilized [Ca2+]i similar to those from healthy donors. Furthermore, we found a decreased percentage of neutrophils depolarizing after stimulation with fMLP and PMA in patients with SCN, whereas membrane depolarization was normal in patients with chNP and cyNP. All the alterations found here are suggested to be caused by a partial immaturity of the neutrophils, although in vivo activation and a direct effect of G-CSF on myeloid precursors might be involved.

Evaluation of flow cytometric methods for diagnosis of chronic granulomatous disease variants under routine laboratory conditions

Neutrophils from 50 pediatric patients with normal phagocyte functions, from 150 healthy adults, from 10 chronic granulomatous disease (CGD)-patients (4 CGD+), and from 18 X-linked carriers for CGD have been tested for their production of H2O2 using staining with dihydrorhodamine 123 and subsequent flow cytometry. Additionally, neutrophils from three patients with myeloperoxidase deficiency were assessed. Cells were activated to produce H2O2 by the phorbol ester phorbol-myristate-acetate (PMA) and by phagocytosis of Escherichia coli bacteria. To evaluate the sensitivity of the method, H2O2-production by neutrophils which was inhibited by different concentrations of diphenyljodonium (DPI) was measured. The results were compared to those from other methods (NBT-testing, cytochrome c-reduction, and especially chemiluminescence). Normal values and ranges of scatter profile were evaluated in terms of peak channel fluorescence: 97% > 700, x = 840 +/- 59 (S.D.), 97% < 890, for pediatric patients. Normal quantitative values also resulted from small blood samples of infants (< 1 year, n = 6, x = 830 +/- 52). For CGD+ (n = 4) the results were clearly far below the normal range. In indicating decreased production of reactive oxygen intermediates the method was at least as sensitive as lucigenin enhanced chemiluminescence. Cytochrome b558-expression of neutrophils from patients and healthy controls was established by flow cytometry following staining with the monoclonal antibody 7D5. The normal range was 97% > 485, 97% < 680, peak channel fluorescence. We conclude that flow cytometric routine diagnostics of CGD can easily enhance the reliability of recognition and the yield of information about this disease compared to conventional methods.

Altered surface marker expression and function of G-CSF-induced neutrophils from test subjects and patients under chemotherapy

We have previously reported an altered surface marker expression and chemotaxis of G-CSF-induced neutrophils from patients with severe congenital neutropenia. However, effects of G-CSF and influence of the underlying disease on neutrophils could not be discerned. In this study we have evaluated the effects of G-CSF on neutrophil phenotype and function in patients under chemotherapy and in healthy test subjects. We found a significantly enhanced expression of Fc gamma RI, CD14 and CD54 and a decrease in the level of Fc gamma RIII during G-CSF treatment. In addition, motility of G-CSF-induced neutrophils was significantly decreased. The effects were seen in patients under cytotoxic chemotherapy and in healthy test subjects. Surface marker alterations and neutrophil motility were affected by G-CSF administration in a dose-dependent manner. Kinetic studies on neutrophils from healthy test subjects demonstrated that all effects could be seen after a single administration of 300 micrograms G-CSF and began to appear within 4 h. Release of partially immature neutrophils from the bone marrow and indirect activation of these cells by G-CSF are discussed as possible reasons for the findings presented. They demonstrate that G-CSF has profound effects on neutrophil phenotype and function in vivo which might have clinical implications.

Cyclosporine metabolite pattern in blood from patients with acute GVHD after BMT

The cyclosporine (CYA) metabolite patterns in blood were evaluated in patients with liver dysfunction after allogeneic BMT. Fifty-five BMT patients were included in the study until discharge from hospital. Blood trough levels of CYA and 12 of its metabolites were quantified using HPLC. The patients were assigned to three groups: group I (no acute GVHD, n = 23), group II (acute GVHD of the skin and good liver function, overall acute GVHD: grade I: n = 18, grade II: n = 2) and group III (acute GVHD and liver dysfunction, overall acute GVHD: grade II: n = 2, grade III/IV: n = 8). Analysis of the trough blood concentrations of CYA and its metabolites revealed higher concentrations of metabolite AM19 in group III than in the other groups without reaching statistical significance. During acute GVHD of the liver, the metabolites AM19 (p < 0.01), AM1c9 (p < 0.05) and AM1A (p < 0.05) were significantly elevated compared with patients with normal liver function while CYA and all other metabolites did not differ. The CYA metabolite pattern in patients with acute GVHD and liver involvement was identical with that of liver graft patients during acute graft rejection, while the metabolite patterns of the patients without acute GVHD paralleled that of kidney grafted patients with normal liver function. Acute GVHD of the liver leads to an impaired elimination of CYA with increased blood concentrations of single CYA metabolites.(ABSTRACT TRUNCATED AT 250 WORDS)