Mature Eosinophils Research Articles

Combined vaccination against IL-5 and eotaxin blocks eosinophilia in mice

Interleukin-5 (IL-5) is a cytokine which is essential for the maturation of eosinophils in bone marrow and for their release into the blood. Eotaxin is a CC type chemokine implicated in the recruitment of eosinophils in a variety of inflammatory disorders. Since eosinophil-activity is governed by these two pathways, we targeted both IL-5 and eotaxin by active vaccination to block eosinophilia. We produced two vaccines by chemically cross-linking IL-5 or eotaxin to a virus-like particle (VLP) derived from the bacteriophage Qβ, yielding highly repetitive arrays of these cytokines on the VLP surface. Both vaccines overcame self-tolerance and induced high antibody titers against the corresponding self-molecules in mice. Immunization with either of the two vaccines reduced eosinophilic inflammation of the lung in an ovalbumin (OVA) based mouse model of allergic airway inflammation. Animals immunized with the two vaccines at the same time developed high antibody titers against both cytokines and also reduced eosinophil-infiltration of the lung. These data demonstrate that targeting either IL-5 or eotaxin may lower eosinophilia. Simultaneous immunization against IL-5 and eotaxin demonstrates that such a therapeutic approach may be used to treat complex disorders in which multiple mediators are involved.

An investigation of the clinical utility of serum interleukin-5 measurements in bronchial asthma patients

Bronchial asthma has been identified as a chronic inflammatory airway disorder associated with cell infiltration (mainly eosinophils) and airway epithelial cell detachment caused by the activation of infiltrated cells. Interleukin-5 (IL-5), a cytokine closely related to the production and activation of eosinophils, has been shown to induce the proliferation and differentiation of eosinophils, prolong their survival, and to enhance the functions of mature eosinophils. We monitored clinically the changes in serum IL-5 concentrations in patients with bronchial asthma both during and after asthma attacks. The relationship serum IL-5 concentrations and the type and severity of bronchial asthma, as well as eosinophil counts in sputum, was investigated. We also measured changes in IL-5 concentrations during steroid therapy. IL-5 concentrations were significantly decreased during asthma attacks and after their relief (p < 0.001). An analysis of blood samples taken from 55 patients suffering asthma attacks showed that serum IL-5 concentrations were significantly higher in non-atopy-type asthma than in atopy-type asthma (p < 0.05). Serum IL-5 levels are highest in severe asthma, followed by moderate asthma (p < 0.001) and mild asthma (p < 0.001). Serum IL-5 concentrations during asthma attacks and eosinophil counts in sputum were closely correlated (r = 0.85). Serum IL-5 concentrations were below the limit of determination and decrease the number of eosinophils in sputum was noted in 15 patients whose asthma was well-controlled by the long-term inhalation of beclometasone. Serum IL-5 concentrations did not decrease below the limit of determination (even during attack-free periods) in patients whose disease could not be well controlled by 6-month inhalation therapy with beclometasone. In patients with major and moderate bronchial asthma attacks, serum IL-5 concentrations decreased as symptoms improved over time following the i.v. infusion of steroids, suggesting that steroids are effective in inhibiting the production of IL-5. Measurement serum IL-5 concentrations could be clinically useful in the determination of the pathology (e.g., severity) of bronchial asthma could serve as an index for the degree of control of asthma, and may be useful in determining the disease's long-term prognosis.

Fractionation of Mature Eosinophils in GATA-Reporter Transgenic Mice

Eosinophils contribute to the pathophysiology of allergic and infectious diseases, albeit their molecular functions remain unknown. Mature eosinophils are identified by their unique morphology and staining characteristics. However, it is difficult to fractionate living eosinophils by flow cytometry because these granulocytes express multiple cell surface markers that are shared by other cells of hematopoietic or non-hematopoietic origin. In this study, we describe a flow cytometry-based method to enumerate and fractionate eosinophils by developmental stages. To fractionate these cell types, we used transgenic mouse lines that express fluorescent proteins under control of the Gata1 gene hematopoietic regulatory region (Gata1-HRD), which is exclusively active in Gata1-expressing hematopoietic cells, including eosinophils. As expected, mature eosinophils were highly enriched in the fluorescent reporter-expressing subfraction of bone marrow myeloid cells that were negatively selected by using multiple antibodies against B220, CD4, CD8, Ter119, c-Kit and CD71. Cytochemical analyses of flow-sorted cells identified the cells in this fraction as eosinophils harboring eosinophilic granules. Additionally, expression of eosinophil-specific genes, for instance eosinophil enzymes and the IL-5 receptor alpha gene, were specifically detected in this fraction. The expression of these eosinophil-specific genes increased as the cells differentiated. This method for enrichment of bone marrow eosinophils is applicable to fractionation of eosinophils and bronchoalveolar lavage fluid from transgenic mice with atopic asthma. Thus, both pathological and developmental stages of eosinophils are efficiently fractionated by this flow cytometry-based method using Gata1-HRD transgenic reporter mice. This study, therefore, proposes a useful means to study the experimental allergic and inflammatory systems.

Evidence for a regulatory role of α4 – integrins in the maturation of eosinophils generated from the bone marrow in the presence of dexamethasone

Although eosinophils co-express multiple integrin receptors, the contributions of integrins to eosinophil development have not been explored. We previously described extensive aggregation and cytological immaturity in eosinophils developing in bone-marrow (BM) cultures exposed to dexamethasone. Here we examined the relationship of alpha 4 integrins with these effects of dexamethasone. We evaluated: (a) the effects of exposure to dexamethasone in BM culture on eosinophil expression of alpha 4 integrin receptors and ligands; (b) the contribution of alpha 4 integrins to eosinophil aggregation and maturation. Cultures were established with IL-5 (alone or with dexamethasone) for up to 7 days, and eosinophil production, alpha 4 integrin receptor/ligand expression, aggregation and morphology were evaluated before and after targeting alpha 4 integrin-dependent adhesions. Because prostaglandin E2 (PGE2) modifies the effects of dexamethasone on eosinophilopoiesis, PGE2 effects on alpha 4 integrin expression and function were also evaluated. Dexamethasone increased the yield of eosinophils up to day 7. The frequency of eosinophils expressing alpha 4, beta1 and beta 7 integrin receptors at day 7 was also increased by dexamethasone. Eosinophils also expressed the alpha 4 beta 1 ligand, VCAM-1. Dexamethasone increased the expression of alpha 4 integrin and VCAM-1 in aggregates containing eosinophils as early as day 3. PGE2, added up to day 3, modified the effects of dexamethasone to suppress the expression of alpha 4 integrin, decrease aggregation and promote cytological maturation of eosinophils recovered at day 7. Dissociation of immature eosinophils from clusters present at day 3 by reagents targeting alpha 4 or beta1 integrins or VCAM-1 also induced cytological maturation. The concordant effects of targeting alpha 4 integrins with drugs and antibodies support a relationship between alpha 4-mediated aggregation and maturational arrest. These observations support a novel role for alpha 4 integrin receptors and ligands in eosinophilopoiesis. In addition, increased alpha 4 expression following glucocorticoid exposure may contribute to the retention and accumulation of eosinophils in haemopoietic tissue.

Airway smooth muscle: telling the eosinophil how to behave

Airway smooth muscle: telling the eosinophil how to behave

Human airway smooth muscle promotes eosinophil differentiation

Human airway smooth muscle (HASM) cells in culture synthesize cytokines and chemokines that may orchestrate the tissue homing and in situ differentiation of haemopoietic progenitor cells from the peripheral circulation. To study the effect of a supernatant from cultured HASM cells on the differentiative and transmigrational responses of haemopoietic progenitor cells. HASM cells were grown to confluence and stimulated with a cytomix of TNF-alpha, IL-1beta and IFN-gamma. Peripheral blood-derived progenitors from atopic asthmatics (n=12) and non-atopic controls (n=11) were grown in a methylcellulose culture with a supernatant from stimulated HASM cells to assess clonogenic potential. The ability of HASM cells to stimulate directional migration and adhesion to fibronectin of blood progenitors was also investigated. HASM cells stimulated significant growth of eosinophil/basophil colony forming units (Eo/B CFUs) from blood progenitor cells from both groups of subjects. This activity was significantly attenuated in the presence of anti-IL-5 and anti-granulocyte macrophage-colony forming factor blocking antibodies and by pre-treatment with SB202190 [p38 mitogen-activated protein kinase (MAPK) inhibitor]. An src kinase (srcK) inhibitor (Pyrazolopyrimidine 1) was less effective at attenuating IL-5- and HASM-stimulated Eo/B CFU growth from both groups of subjects. Examination of the phosphorylation of these kinases in CD34(+) cells following co-incubation with the major constituents of HASM showed activation of p38 MAPK but not that of the srcK pathway. The HASM supernatant had no significant effect on the migrational and adhesive responses of haemopoietic progenitor cells in vitro. We have shown that HASM cell-derived cytokines promote eosinophil differentiation that is dependent on p38 MAPK but not on the srcK pathway. This study shows that a major structural cell of the lungs, airway smooth muscle, has the capability to direct eosinophil differentiation and maturation from progenitor cells, which in turn may perpetuate an eosinophilic inflammation and consequently tissue remodelling in patients with chronic asthma.

Mature human eosinophils express functional Notch ligands mediating eosinophil autocrine regulation

AbstractEosinophil chemotaxis and survival within tissues are key components in the development of tissue eosinophilia and subsequent effector responses. In this study, we demonstrate a novel mechanism of eosinophil autoregulation affecting migration and survival mediated through Notch signaling. We show for the first time that human blood eosinophils express Notch receptors and Notch ligands, expressions of which are influenced by the presence of eosinophil-activating granulocyte-macrophage colony-stimulating factor (GM-CSF). Evidence of Notch receptor activation and subsequent transcription of the Notch-responsive gene HES1 were observed in GM-CSF–stimulated eosinophils, confirming functionality of eosinophil-expressed Notch-signaling components. Moreover, by inhibiting Notch signaling with γ-secretase inhibitors or Notch receptor–specific neutralizing antibodies, we demonstrate that autocrine Notch signaling enhances stimulus-mediated actin rearrangement and eosinophil chemokinesis, and impairs eosinophil viability. Taken together, these data suggest autocrine Notch signaling, enhanced in response to tissue- or inflammatory-derived signals, influences eosinophil activity and longevity, which may ultimately contribute to the development of tissue eosinophilia and exacerbation or remediation of eosinophil effector functions.

Mepolizumab in the treatment of eosinophilic esophagitis

Mepolizumab is a humanized monoclonal antibody that binds specifically to and inactivates a protein cell messenger termed IL-5, which plays a major role in the proliferation, maturation, activation and survival of eosinophils. As a result, mepolizumab has been studied in a number of eosinophil-associated diseases, such as asthma, hypereosinophilic syndrome and eosinophilic esophagitis (EE). EE is a clinical entity characterized by eosinophilic infiltration of the esophagus (≥15 eosinophils/high power field in one or more fields) in the absence of gastroesophageal reflux. EE is on the rise, and this can not be fully accounted for by increased recognition. Currently, available therapies, although successful in many cases, can be disappointing in some patients, whether from lack of response, negative impact on quality of life, or significant toxicity. In order to better define EE therapy, investigators are evaluating novel drugs, including anti-IL-5 agents such as mepolizumab. Mepolizumab has been demonstrat...

Macrophage migration inhibitory factor is critical to interleukin‐5‐driven eosinophilopoiesis and tissue eosinophilia triggered by Schistosoma mansoni infection

Macrophage migration inhibitory factor (MIF) participates in the pathogenesis of inflammatory diseases, including asthma, in which it enhances airway hypersensitivity and tissue eosinophilia. Herein, we investigated the role of MIF in eosinophilopoiesis and tissue eosinophilia using Schistosoma mansoni infection. MIF-deficient (Mif(-/-)) mice had similar numbers of adult worms, eggs, and granulomas compared to wild-type mice, but the size of granulomas was strikingly reduced due to smaller numbers of eosinophils. MIF did not affect the acquired response to infection, as Mif(-/-) mice produced normal amounts of Th2 cytokines and IgE. Nevertheless, recombinant MIF (rMIF) behaved as a chemoattractant for eosinophils, what could partially explain the reduced eosinophilia in infected Mif(-/-) mice. Moreover, the percentage of eosinophils was reduced in bone marrows of Mif(-/-) mice chronically infected with S. mansoni compared to wild type. Mif(-/-) had impaired eosinophilopoiesis in response to interleukin (IL)-5 and addition of rMIF to bone marrow cultures from IL-5 transgenic mice enhanced the generation of eosinophils. In the absence of MIF, eosinophil precursors were unable to survive the IL-5-supplemented cell culture, and were ingested by macrophages. Treatment with pancaspase inhibitor z-VAD or rMIF promoted the survival of eosinophil progenitors. Together, these results indicate that MIF participates in IL-5-driven maturation of eosinophils and in tissue eosinophilia associated with S. mansoni infection.

Primary eosinophilic disorders of the gastrointestinal tract

Eosinophils are important effector cells of the innate immune system. Eosinophilic infiltrative disorders of the gastrointestinal tract, though recognised for decades, have recently witnessed a resurgence of interest, particularly for...

Asthma progression to airway remodeling and bone marrow eosinophil responses in genetically distinct strains of mice

Patient factors that cause long-term airway remodeling are largely unidentified. This suggests that genetic differences may determine which asthmatic patients develop airway remodeling. A murine model with repeated allergen exposure leading to peribronchial fibrosis in complement factor 5 (C5)-deficient A/J mice has been used to study asthma progression. No studies have addressed the systemic effects of allergen sensitization or chronic allergen exposure on bone marrow eosinophilopoiesis in this mouse strain. To investigate bone marrow eosinophil responses during acute sensitization and chronic allergen exposure using genetically distinct mouse strains differing in persistent airway reactivity and remodeling. The C5-sufficient BALB/c and C5-deficient A/J mice were repetitively exposed to intranasal ovalbumin for 12 weeks. Subsequently, the mice were evaluated for airway eosinophilia, mucus-containing goblet cells, and peribronchial fibrosis. Both strains of mice were also acutely sensitized to ovalbumin. Bone marrow eosinophil progenitor cells and mature eosinophils were enumerated. BALB/c and A/J mice have similar bone marrow responses after acute allergen exposure, with elevations in bone marrow eosinophil progenitor cell and eosinophil numbers. After chronic allergen exposure, only C5-deficient A/J mice that developed peribronchial fibrosis exhibited bone marrow eosinophilia. BALB/c mice lacked peribronchial fibrosis and extinguished accelerated eosinophil production after long-term allergen challenge. Chronic airway remodeling after repeated allergen exposure in genetically different mice correlated with differences in long-term bone marrow eosinophilopoiesis. Preventing asthma from progressing to chronic airway remodeling with fibrosis may involve identifying genetically determined influences on bone marrow responses to chronic allergen exposure.

Post-translational Tyrosine Nitration of Eosinophil Granule Toxins Mediated by Eosinophil Peroxidase

Nitration of tyrosine residues has been observed during various acute and chronic inflammatory diseases. However, the mechanism of tyrosine nitration and the nature of the proteins that become tyrosine nitrated during inflammation remain unclear. Here we show that eosinophils but not other cell types including neutrophils contain nitrotyrosine-positive proteins in specific granules. Furthermore, we demonstrate that the human eosinophil toxins, eosinophil peroxidase (EPO), major basic protein, eosinophil-derived neurotoxin (EDN) and eosinophil cationic protein (ECP), and the respective murine toxins, are post-translationally modified by nitration at tyrosine residues during cell maturation. High resolution affinity-mass spectrometry identified specific single nitration sites at Tyr349 in EPO and Tyr33 in both ECP and EDN. ECP and EDN crystal structures revealed and EPO structure modeling suggested that the nitrated tyrosine residues in the toxins are surface exposed. Studies in EPO(-/-), gp91phox(-/-), and NOS(-/-) mice revealed that tyrosine nitration of these toxins is mediated by EPO in the presence of hydrogen peroxide and minute amounts of NOx. Tyrosine nitration of eosinophil granule toxins occurs during maturation of eosinophils, independent of inflammation. These results provide evidence that post-translational tyrosine nitration is unique to eosinophils.

IFN Consensus Sequence Binding Protein (Icsbp) Is Critical for Eosinophil Development

IFN consensus sequence binding protein (Icsbp) (IFN response factor-8) is a hematopoietic transcription factor with dual functions in myelopoiesis and immunity. In this study, we report a novel role of Icsbp in regulating the development of eosinophils. Loss of Icsbp in mice leads to a reduction of eosinophils in different tissues. During parasite infection with the nematode Nippostrongylus brasiliensis, Icsbp-deficient mice fail to mount eosinophilia despite a vigorous IL-5 response. Numbers of phenotypically defined eosinophil progenitors are decreased and those progenitors have, on a per-cell basis, reduced eosinophil differentiation potential. The transcription factor Gata1, crucial for eosinophil development, is reduced expressed in committed eosinophil progenitors in wells as mature eosinophils. These findings identify Icsbp as a novel transcription factor critical for the development of the eosinophil lineage.

Marginal Zone B-cell Lymphoma Arising from Buccal Mucosa Resembling Inflammatory Myofibroblastic Tumor of the Soft Tissue

We report here a case of marginal zone B-cell lymphoma (MZBL) arising from buccal mucosa resembling inflammatory myofibroblastic tumor (IMT) of the soft tissue. On a low-power field, the lesion is characterized by fibrous granulation tissue and numerous lymphoid follicles with or without atrophic small germinal center. A portion of the lymphoid follicles were surrounded by partial and/or complete thin pale cuff of centrocyte-like (CCL) cells on high power field. The thin rim of the lymphoid follicles contained CCL-cells, plasma cells, cells showing plasma cell differentiation and mature eosinophils. In contrast, the granulomatous areas contained were characterized by haphazardly arranged spindle cells, mature plasma cells, mature eosinophils, small-to-medium lymphocytes and histiocytes. Histologically, IMT was suspected. However, flow cytometry and immunohistochemical study demonstrated a monotypic nature of centrocyte-like cells, plasma cells and their precursor and confirmed the diagnosis of MZBL arising from the buccal mucosa. The differential diagnostic problems between IMT of the soft tissue and classical Hodgkin lymphoma and T-cell lymphoma have been discussed previously. However, the present case indicated that MZBL should be added to the differential diagnosis of IMT of the soft tissue.

Cytochemistry and morphology of granulocytes of the caecilian Siphonops annulatus (Amphibia, Gymnophiona)

The caecilians (Amphibia, Gymnophiona) constitute one of the least known groups of terrestrial vertebrates because most species live underground in quite inaccessible environments. Siphonops annulatus is an exclusively fossorial species and is the most extensively distributed caecilian in South America. Little is known of this order concerning circulating granulocytes, including their morphological and cytochemical structure and ultrastructure. This paper is part of a project covering the study of granulocytes in representative species of the order Amphibia. Blood extensions were carried out and submitted to Leishman, Toluidine Blue, Periodic acid Schiff, Sirius Red and hydrogen o-toluidine peroxide methods. Part of the samples was prepared for conventional transmission electron microscopy. Among granular leukocytes, mature and immature neutrophils and eosinophils were identified, plus basophils. The most frequent granulocyte encountered in S. annulatus peripheral blood is the neutrophil. This is a cell with a hyper-segmented nucleus and with a very clear cytoplasm when compared to the eosinophil, which presents large cytoplasmic acidophilic granules. On the other hand, the basophils present basophilic and metachromatic granules. Glycogen was detected in the cytoplasm of the neutrophils and eosinophils, while basic protein rich in amino acids was observed in the eosinophil’s granules. Myeloperoxidase activity was detected in the cytoplasm of the neutrophils and eosinophils. Neutrophils were ultrastructurally detected with three types of small granules: eosinophils with large and small spherical granules and basophils with large spherical granules with lamellate structures.

Mepolizumab

Mepolizumab is an anti-interleukin-5 monoclonal antibody that is in clinical trials with GlaxoSmithKline (GSK) for the treatment of severe asthma, nasal polyposis and hypereosinophilic syndrome and eosinophilic oesophagitis (the latter two indications are classed as eosinophilia in the phase table). Interleukin-5 stimulates the production, activation and maturation of eosinophils. Since mepolizumab inhibits interleukin-5 and has a long terminal half-life, treatment with mepolizumab causes a sustained reduction in the numbers of circulating eosinophils. Thus, mepolizumab may be a useful therapeutic agent for the treatment of conditions characterized by increased levels of eosinophils. Hypereosinophilic syndrome is a rare idiopathic disease with broad clinical signs and symptoms that is diagnosed based on a persistent blood eosinophil count of >1500 cells, various end-organ damages (including skin, heart, lung, nervous system and digestive system), and with exclusion of known secondary causes of hypereosinophilia. Mepolizumab is in clinical trials for the treatment of hypereosinophilic syndrome, eosinophilc oesophagitis, severe asthma (in patients with airway eosinophilia) and nasal polyposis. GlaxoSmithKline (GSK) has completed enrolment in a phase II study of mepolizumab in 20 patients with symptomatic eosinophilic bronchitis with or without asthma in Canada. The randomized, double-blind, placebo-controlled study is evaluating the effects of intravenous mepolizumab on asthma control, airway eosinophilia and the degree to which concomitant corticosteroid treatment can be reduced (NCT00292877). In previous clinical studies, including trials in the EU and US, mepolizumab has shown a lack of effect on allergen-induced airway responses and inflammation despite a significant reduction in blood and sputum eosinophil levels.A randomized, double-blind, placebo-controlled, multicentre, phase III study of mepolizumab over 9 months in 85 patients with hypereosinophilic syndrome was completed in 2006. All patients have been offered, and continued in, a phase III, open-label, long-term extension study of mepolizumab. Enrolment in this study was completed in September 2006.A phase III, compassionate use trial of mepalizumab (NCT00244686) in patients with hypereosinophilic syndrome was ongoing in October 2007 in the US. Patients who have significant clinical disease but are unresponsive to traditional treatment and those who have demonstrated clinical benefit from previous anti-IL-5 treatment are eligible to take part in the trial. Mepolizumab received orphan drug status for first-line treatment in patients with hypereosinophilic syndrome in the US and the EU in 2004. Mepolizumab is also in phase I/II clinical development for the treatment of eosinophilic oesophagitis. A phase I/II trial (NCT00358449) began in August 2006 in the US, Australia, the UK and Canada, and will enrol approximately 72 paediatric patients with eosinophilic oesophagitis. The randomized, parallel-group clinical trial will evaluate the safety, tolerability, pharmacokinetics and pharmacodynamics of intravenous mepolizumab for 12 weeks. In September 2006, GSK completed enrolment in a phase I/II study of mepolizumab for the treatment of eosinophilic oesophagitis in ten adult patients in Switzerland (NCT00274703). The randomized, double-blind, placebo-controlled study will evaluate the pharmacokinetics, pharmacodynamics, safety and tolerability of IV mepolizumab.A phase I/II trial of mepolizumab in four patients with eosinophilic oesophagitis conducted by Cincinnati Children's hospital found the monoclonal antibody was safe and effective. Brigham and Women's Hospital in association with GSK is conducting a phase I/II trial of mepolizumab in patients with Churg-Strauss Syndrome (CSS) in the US. The trial, which started in September 2007, will evaluate the potential of mepolizumab to reduce the need for corticosteroid therapy in patients with CSS (NCT00527566). CSS, otherwise known as allergic granulomatosis, is defined by patients with asthma, eosinophilia and vasculitis.

Mechanisms for the proliferation of eosinophilic leukemia cells by FIP1L1-PDGFRα

The constitutively activated tyrosine kinase Fip1-like 1 (FIP1L1)-platelet-derived growth factor receptor α (PDGFRα) causes eosinophilic leukemia EoL-1 cells to proliferate. Recently, we demonstrated that histone deacetylase inhibitors suppressed this proliferation and induced the differentiation of EoL-1 cells into eosinophils in parallel with a decrease in the level of FIP1L1-PDGFRα. In this study, we analyzed the mechanism by which FIP1L1-PDGFRα induces the proliferation and whether the suppression of cell proliferation triggers the differentiation into eosinophils. The FIP1L1-PDGFRα inhibitor imatinib inhibited the proliferation of EoL-1 cells and decreased the level of the oncoprotein c-Myc as well as the phosphorylation of extracellular signal-regulated kinase and c-Jun N-terminal kinase (JNK). The proliferation of EoL-1 cells and expression of c-Myc were also inhibited by the MEK inhibitor U0126 and JNK inhibitor SP600125. The expression of the eosinophilic differentiation marker CCR3 was not induced by imatinib. These findings suggest that FIP1L1-PDGFRα induces the proliferation of EoL-1 cells through the induction of c-Myc expression via ERK and JNK signaling pathways, but is not involved in the inhibition of differentiation toward mature eosinophils.

Syndrome d’hyperéosinophilie idiopathique aigu chez un rottweiler

The idiopathic hypereosinophilic syndrome is a part of the yet rather unknown diseases and the aetiology remains at the least hypothetical. This syndrome is characterized by a variable hypereosinophilemia as well as a massive infiltration of several organs by mature eosinophils, causing an important tissue damage leading to organ dysfunctions and resulting in the patient death. In this reported case, the acute idiopathic hypereosinophilic syndrome was diagnosed in a 4-year rottweiler female dog based on an increased eosinophilemia and the infiltration of stomach, small intestine, colon, pancreas, spleen, ganglions, skin, lungs and bone marrow by mature eosinophiles. The acute development of the disease precluded any therapeutical hope success.

Systemic mastocytosis associated with small lymphocytic lymphoma: An incidental finding in a patient with invasive gastric adenocarcinoma

Mastocytosis comprises a heterogeneous group of disorders characterized by the abnormal growth and accumulation of mast cells in various tissues. We report an interesting case of systemic mastocytosis diagnosed incidentally in an omental lymph node in the setting of an invasive gastric adenocarcinoma. The Diff-Quick touch preparation of the lymph node revealed abundant single cells and loose aggregates of cells with round to oval nuclei and deeply basophilic granules. Monotonous proliferation of small mature lymphocytes and many eosinophils were also present in the background. No evidence of metastatic carcinoma was seen. The frozen section and permanent sections of lymph node showed partial to complete replacement of lymph node by neoplastic mast cells. We present the cytologic findings of this unique case in addition to a brief discussion of systemic mastocytosis in the setting of another malignancy.

Eosinophils from Lineage-Ablated ΔdblGATA Bone Marrow Progenitors: The dblGATA Enhancer in the Promoter of GATA-1 Is Not Essential for Differentiation Ex Vivo

A critical role for eosinophils in remodeling of allergic airways was observed in vivo upon disruption of the dblGATA enhancer that regulates expression of GATA-1, which resulted in an eosinophil-deficient phenotype in the DeltadblGATA mouse. We demonstrate here that bone marrow progenitors isolated from DeltadblGATA mice can differentiate into mature eosinophils when subjected to cytokine stimulation ex vivo. Cultured DeltadblGATA eosinophils contain cytoplasmic granules with immunoreactive major basic protein and they express surface Siglec F and transcripts encoding major basic protein, eosinophil peroxidase, and GATA-1, -2, and -3 to an extent indistinguishable from cultured wild-type eosinophils. Fibroblast coculture and bone marrow cross-transplant experiments indicate that the in vivo eosinophil deficit is an intrinsic progenitor defect, and remains unaffected by interactions with stromal cells. Interestingly, and in contrast to those from the wild type, a majority of the GATA-1 transcripts from cultured DeltadblGATA progenitors express a variant GATA-1 transcript that includes a first exon (1E(B)), located approximately 3700 bp downstream to the previously described first exon found in hemopoietic cells (1E(A)) and approximately 42 bp upstream to another variant first exon, 1E(C). These data suggest that cultured progenitors are able to circumvent the effects of the DeltadblGATA ablation by using a second, more proximal, promoter and use this mechanism to generate quantities of GATA-1 that will support eosinophil growth and differentiation.