Search

Eosinophilic granulocytes are a subpopulation of leucocytes and part of the innate immune cell pool. Additionally, they have homeostatic functions in different tissues. Classically, an increased number of eosinophils is associated with allergies and parasitic infections; however, eosinophilia can also be found in vasculitides and malignant tumors. The most important controlling factors of eosinophils are the cytokine interleukin 5 and eotaxins. Eosinophils are able to produce a broad range of signalling factors and toxic proteins, which are stored in cytoplasmic granules and can be quickly and specifically released when needed depending on the stimulus. To combat pathogens, eosinophils can catapult extracellular traps consisting of mitochondrial DNA and toxic proteins into the intercellular space. This review focuses on the basic structure, control and function of eosinophils in health and disease.

Based on a case report an overview on the differential diagnostic considerations with respect to blood hypereosinophilia (HE) and hypereosinophilic syndromes (HES) in childhood is given. A 13-year-old boy was admitted for the clarification of an asthma. In the blood count an increased HE with 3 500/µl (30%) was found along with elevated total serum IgE and IL-5 level (2 000 IU/ml and 17 pg/ml). Lung function showed an obstruction (FEV1 38%). Radiologically the picture of bronchiectasis and mucus pluggine appeared. In the BAL a HE (76%) with raised IL-5 level was apparent. Histologically asthma was diagnosed with mucostasis, hypertrophy of the bronchial wall musculature and a lung HE. Differential-diagnostically an ABPA, a Churg-Strauss-Syndrome, a parasitosis, drug associated HE, allergies and malignant disease could be excluded. An aberrant T-cell clone in peripheral blood was detected by flow cytometry and T-cell receptor clonal rearrangements by PCR, leading to the diagnosis of a lymphoid variant of HES (L-HES). Failure to detect the FIP1L1-PDGFRA gene fusion and a normal bone marrow examination could exclude a neoplastic HES (HESN). After steroid initiation, prompt decrease of blood eosinophilia with resolution of symptoms was observed. Steroid discontinuation led to eosinophilia recurrence associated with disease symptoms. As steroid-sparing agent the immunosuppressive azathioprine was additionally given; steroid doses could be decreased and stopped in the course. This case demonstrated the range of HE evaluation in infancy. With asthma one should also consider the possibility of a L-HES.

BACKGROUND Intravenous immunoglobulin (IVIG) preparations are increasingly used for the treatment of autoimmune and chronic inflammatory diseases. Naturally occurring autoantibodies against Siglec 9 and Fas are thought to contribute to the anti inflammatory effects of IVIG via cell death regulation of leukocytes and tissue cells. Dimeric IVIG fractions are suspected to contain idiotypic (Id) anti idiotypic complexes of antibodies which might also include anti Siglec 9 and anti Fas autoantibodies. METHODS Dimeric IVIG fractions were separated from monomeric IVIG by size exclusion chromatography and remonomerized by low pH treatment. Binding studies of total monomeric and dimeric IVIG were performed using surface plasmon resonance and flow cytometry on primary human neutrophils. RESULTS Anti Siglec 9 and anti Fas autoantibodies were contained in both monomeric and dimeric IVIG fractions but anti Siglec 9 antibodies were highly enriched in dimeric IVIG. The propensity to engage in dimer formation was paratope dependent. IVIG binding to Siglec 9 was specific and sialylation independent. Interestingly we detected anti idiotypic antibodies (anti Ids) against anti Siglec 9 autoantibodies in dimeric but not in monomeric fractions of IVIG. CONCLUSIONS Our study supports the concept that idiotype anti idiotype (Id anti Id) interactions contribute to the dimer formation in IVIG preparations. To our knowledge this is the first description of Id anti Id dimers of death receptor specific antibodies in IVIG. Such Id anti Id interactions might determine the activity of immunomodulatory antibodies present both in IVIG and the patient.

Im Jahre 1879 stellte Paul Ehrlich erstmals eine starke Affinität einer bis dahin namenlosen, als grobkörnig granuliert (Wharton 1846) beschriebenen Blutzelle für den Farbstoff Eosin fest. Dieses Färbeverhalten war in der Folge namensgebend für den Eosinophilen (Ehrlich 1879).

The hypereosinophilic syndromes are rare disorders in childhood and require extensive differential diagnostic considerations. In the last years the earlier "idiopathic HES" called syndromes could be differentiated into molecular biologically, immunophenotypically and clinically more characterized heterogeneous diseases with high therapeutic and prognostic relevance. Nowadays the term HES summarizes diseases, which go hand in hand with a local or systemic hypereosinophilia (HE) connected with an organ damage. Depending on the cause of the HE one differentiates primary/neoplastic HES (HESN) from secondary/reactive HES (HESR). The latter develops reactively in connection with allergies, parasitosis, medications, neoplasia or a clonal increase of T-lymphocytes among others. With HESN the HE results from a clonal increase of eosinophilic granulocytes. While for some subgroups of the HESN (among others FIP1L1-PDGFRA fusion gene) the administration of a tyrosine kinase inhibitor is a new and effective therapy option, glucocorticoids still represent the medication of first choice for many not PDGFRA associated variants. Different immunomodulatory drugs or cytostatic agents are necessary to allow dose reduction of glucocorticoids. The promising therapy with anti-IL-5 antibodies is still not approved in infancy, could however become a treatment option in the future. Due to the present lack of knowledge about the HES in infancy the establishment of a register should be aimed for the treatment of HES in infancy.

Apoptosis is the most common form of physiologic cell death and a necessary process to maintain cell numbers in multicellular organisms. Eosinophils are constantly produced in the bone marrow and the same numbers die, under normal circumstances, within a relatively short time period. In many eosinophilic inflammatory diseases, reduced eosinophil apoptosis has been described. This mechanism may contribute to increased eosinophil numbers, a phenomenon called eosinophilia. Overexpression ofIL-5 appears to be crucial for delaying eosinophil apoptosis in many allergic disorders. Survival factor withdrawal leads to the induction of apoptosis. Besides survival cytokines, eosinophil apoptosis is also regulated by death factors. Recent observations suggest a role for mitochondria in conducting eosinophil apoptosis, although the mechanisms that trigger mitochondria to release proapoptotic factors remain less clear. Drugs that specifically induce eosinophil apoptosis might be useful for triggering the resolution of unwanted eosinophilic inflammatory responses.

Interleukin-5 (IL-5) is an eosinophil differentiation factor. Therefore, increased levels of IL-5 in the bone marrow is associated with increased eosinophil numbers in blood. In addition, IL-5 increases the sensitivity ofeosinophils towards other stimuli and delays their cell death. In contrast to other cytokines, IL-5 acts on a limited number of cells only. In fact, high-affinity IL-5 receptors are exclusively expressed by eosinophils and basophils, but no other human cells. Therefore, neutralization of IL-5 appears to be an obvious approach to treat eosinophilic disorders, since no major side effects due to effects on other cells are expected. Results from animal experiments suggested that anti-IL-5 antibodies may have anti-asthmatic activities. In this article, I summarize our current knowledge regarding anti-IL-5 therapy and speculate on the potential use of these drugs in the future.

Die zunehmenden Kenntnisse uber die zellularen und molekularen Mechanismen der Immunabwehr haben sehr viel auch zum Verstandnis der Pathogenese des Asthma bronchiale beigetragen. Bei Asthma bronchiale ist das Immunsystem aktiviert, T-Zellen werden durch Allergene oder andere Antigene chronisch stimuliert. Die aktivierten T-Zellen sind wichtige Quellen fur Zytokine, deren Expression genau reguliert wird. Zytokine regulieren ein ganzes Netz von Immunzellen, ihre Produktion, Funktion und Lokalisation innerhalb des Organismus. Dieser Artikel gibt einen aktuellen Uberblick zur Rolle von Zytokinen bei der Regulation der asthmatischen Immunantwort.

In allergic inflammations of the skin, activation of CD4+ T cells was demonstrated to play an important role; however, a minor role for CD8+ T cells is implied. In the present study, we compared cutaneous lymphocyte-associated Ag (CLA)-expressing CD4+ and CD8+ subsets, which were isolated from peripheral blood and lesional skin biopsies in atopic dermatitis (AD) patients. We demonstrated that CD8+CLA+ T cells proliferate in response to superantigen and are as potent as CD4+CLA+ T cells in IgE induction and support of eosinophil survival. In atopic skin inflammation, the existence of high numbers of CD4+ and CD8+ T cells was demonstrated by immunohistochemistry and by culturing T cells from skin biopsies. In peripheral blood, both CD4+ and CD8+ subsets of CLA+CD45RO+ T cells were in an activated state in AD. The in vivo-activated CLA+ T cells of both subsets spontaneously released an IL-5- and IL-13-dominated Th2 type cytokine pattern. This was confirmed by intracytoplasmic cytokine staining immediately after isolation of the cells from peripheral blood. In consequence, both CD4+ and CD8+, CLA+ memory/effector T cells induced IgE production by B cells mainly by IL-13, and enhanced eosinophil survival in vitro by delaying eosinophil apoptosis, mainly by IL-5. These results indicate that in addition to the CD4+ subset, the CD8+CLA+ memory/effector T cells are capable of responding to superantigenic stimulation and play an important role in the pathogenesis of AD.

In den vergangenen Jahren wurden zahlreiche neue Erkenntnisse zur Biologie eosinophiler Granulozyten, ihrer Rolle für die Gesundheit und bei Krankheiten gewonnen. Differenzierte Kenntnisse zur Pathogenese, neue diagnostische Methoden und Therapeutika haben das Verständnis zur Hypereosinophilie und damit assoziierten Erkrankungen und Syndromen fundamental geändert. In dieser Übersichtsarbeit diskutieren wir die gegenwärtige Klassifikation der Hypereosinophiliesyndrome und neue Therapieansätze., In recent years, the knowledge on eosinophil biology as well as their role in health and disease has dramatically increased. Differential insights in the pathogenesis, new diagnostic techniques and therapeutic substances have modified our understanding of hypereosinophilia and associated diseases and syndromes. In this review, we discuss the current classification of hypereosinophilic syndromes as well as therapeutic strategies.

The function of eosinophils has been attributed to host defense, immunomodulation, and fibrosis. Although eosinophils are found among infiltrating cells in a broad spectrum of skin diseases, their pathogenic role remains uncertain. This study aimed to analyze the cytokine expression by eosinophils in different skin diseases.Skin specimens from different skin diseases [allergic/reactive, infectious, autoimmune, and tumors/lymphomas (LY)] were stained by antibodies directed to eosinophil cationic protein, cytokines [tumor necrosis factor (TNF)-α, interleukin (IL)-5, IL-6, IL-10, IL-11, IL-13, IL-17, IL-25, IL-33, interferon-γ, transforming growth factor (TGF)-β, and thymic stromal lymphopoietin], eotaxins (CCL11, CCL24, and CCL26), metalloproteinase (MMP)-9 as well as extracellular matrix proteins (tenascin-C and procollagen-3) and then analyzed by laser scanning microscopy.The number of eosinophils varied considerably in and between disease groups and did not correlate with the numbers of accompanying inflammatory cells. The expression of IL-5, IL-6, IL-11, TGF-β, CCL24, and MMP-9 by eosinophils significantly differed between disease groups. Eosinophils in tumors/LY predominantly expressed IL-6, TGF-β, and CCL24, but not IL-11. On the other hand, in autoimmune diseases, eosinophils largely contributed to MMP-9 production. IL-5-generating eosinophils were particularly obvious in allergic and infectious diseases.In skin diseases, eosinophil expresses a broad spectrum of cytokines. The different cytokine expression patterns suggest distinct functional roles of eosinophils in these diseases that might be related to host defense, immunomodulation, fibrosis, and/or tumor development.

Udgivelsesdato: 2009-Dec The methodology of randomized clinical trials is essential for the critical assessment and registration of therapeutic interventions. The CONSORT (Consolidated Standards of Reporting Trials) statement was developed to alleviate the problems arising from the inadequate reporting of randomized controlled trials. The present article reflects on the items that we believe should be included in the CONSORT checklist in the context of conducting and reporting trials in allergen-specific immunotherapy. Only randomized, blinded (in particular blinding of patients, health care providers, and outcome assessors), placebo-controlled Phase III studies in this article. Our analysis focuses on the definition of patients' inclusion and exclusion criteria, allergen standardization, primary, secondary and exploratory outcomes, reporting of adverse events and analysis.

Mast cells activation through FcepsilonRI cross-linking has a pivotal role in the initiation of allergic reactions. The influence of this activation on programmed cell death of human mast cells has not yet been clarified. This study evaluates the influence of IgE-dependent activation alone and in synergy with TRAIL on the expression of molecules involved in the apoptotic signal transduction.Human cord blood derived mast cells (CBMC) were cultured with myeloma IgE followed by activation with anti-human IgE. The expression of proteins involved in apoptotic signal transduction was assessed by immunoblot analysis. To test the effect of activation on a pro-apoptotic stimulus, activated, IgE-treated and resting CBMC were incubated with TRAIL, or in a medium with suboptimal concentrations of stem cell factor (SCF).In accordance with a previous study of ours, it was found that IgE-dependent activation increased TRAIL-induced caspase-8 and caspase-3 cleavage. However, it did not have a significant influence on CBMC death induced by SCF withdrawal. IgE-dependent activation increased the expression of FLIP and myeloid cell leukemia 1 (MCL-1) anti-apoptotic molecules as well as the pro-apoptotic one, BIM. In addition, a decrease in BID expression was observed. TRAIL could reverse the increase in FLIP but did not influence the upregulation of MCL-1 and of BIM.These findings suggest that IgE-dependent activation of human mast cells induces an increase in both pro-survival and pro-apoptotic molecules. We therefore hypothesized that IgE-dependent activation may regulate human mast cell apoptosis by fine-tuning anti-apoptotic and pro-apoptotic factors.

Nonallergic rhinitis (NAR) can be defined as a chronic nasal inflammation which is not caused by systemic IgE-dependent mechanisms. It is common and probably affects far more than 200 million people worldwide. Both children and adults are affected. However, its exact prevalence is unknown and its phenotypes need to be evaluated using appropriate methods to better understand its pathophysiology, diagnosis and management. It is important to differentiate between infectious rhinitis, allergic/NAR and chronic rhinosinusitis, as management differs for each of these cases. Characterization of the phenotype, mechanisms and management of NAR represents one of the major unmet needs in allergic and nonallergic diseases. Studies on children and adults are required in order to appreciate the prevalence, phenotype, severity and co-morbidities of NAR. These studies should compare allergic and NAR and consider different age group populations including elderly subjects. Mechanistic studies should be carried out to better understand the disease(s) and risk factors and to guide towards an improved diagnosis and therapy. These studies need to take the heterogeneity of NAR into account. It is likely that neuronal mechanisms, T cells, innate immunity and possibly auto-immune responses all play a role in NAR and may also contribute to the symptoms of allergic rhinitis.

Inflammatory disorders are characterized by an expansion of hematopoietic effector cells. In allergic and parasitic diseases, the cellular infiltrate consists mainly of eosinophils. Several mechanisms are involved in this process, such as increased eosinophil production in the bone marrow, preferential recruitment and Chemotaxis to the site of inflammation, as well as delayed apoptosis [1]. At the site of inflammation,eosinophils release toxic cationic proteins upon stimulation,a process thought to be important in host defense. Tissue damage caused by eosinophil granule proteins may also be important in the pathophysiology of asthma, atopic dermatitis, and other chronic allergie diseases.

Granulocyte apoptosis is crucial for controlling granulocyte number under normal and inflammatory conditions. Reduced apoptosis of different types of granulocytes is one important mechanism for cell accumulation. Which granulocyte subtype expands is largely dependent on the cytokine milieu present at the inflammatory site. Over expression of G-CSF and GM-CSF is associated with neutrophilia, whereas over expression of IL-5 is linked to eosinophilia. Cytokine withdrawal leads to the induction of granulocyte apoptosis, a mechanism which occurs during resolution of inflammation. Besides survival factors, granulocyte apoptosis is also regulated by death factors, which belong to the tumor necrosis factor (TNF)/nerve growth factor (NGF) superfamily. Recent observations suggest that granulocytes can be activated via CD137, a member of the TNF/NGF receptor superfamily. This review summarizes our current knowledge on the potential role of CD137 in the regulation of both neutrophil and eosinophil apoptosis.

Priming of eosinophils with granulocyte-macrophage colony-stimulating factor (GM-CSF) and subsequent stimulation with platelet-activating factor (PAF) or the anaphylatoxin C5a is associated with a rapid production of leukotrienes (LTs) and release of eosinophil cationic protein (ECP).This study was designed to determine the effects of the sesquiterpene esters petasin, isopetasin and neopetasin on LT generation and ECP release in eosinophils in vitro.The model of eosinophil activation described above was used to induce LT production and ECP release. Cells were incubated with petasins and control inhibitors prior to priming and stimulation. To analyse intracellular steps of eosinophil activation and determine potential drug targets, some key signalling events were studied. Activity of cytosolic phospholipase A2 (cPLA(2)) was measured by analysing the generation of arachidonic acid (AA). Translocation of 5-lipoxygenase (5-LO) was observed using immunofluorescence microscopy. Intracellular calcium concentrations [Ca2+]i were measured by a bulk spectrofluorometric assay.Whereas all three compounds inhibited LT synthesis, ECP release from eosinophils was blocked by petasin only, but not isopetasin or neopetasin. Similarly, PAF- or C5a-induced increases in [Ca2+]i were completely abrogated by petasin only, whereas isopetasin and neopetasin had significant lower blocking efficacy. Moreover, only petasin, but not isopetasin or neopetasin, prevented increases in cPLA(2) activity and 5-LO translocation from the cytosolic compartment to the nucleus envelope in calcium ionophore-stimulated eosinophils.These data suggest that different petasins may at least partially block different intracellular signalling molecules. To reduce LT synthesis, isopetasin and neopetasin may act at the level of or distal to 5-LO. In contrast, petasin may inhibit inflammatory effector functions in human eosinophils by disrupting signalling events at the level of or proximal to phospholipase Cbeta (PLCbeta), besides its potential inhibitory activity within mitogen-activated protein kinase (MAPK) and LT pathways.

Apoptosis is the most common form of physiologic cell death and a necessary process to maintain cell numbers in multicellular organisms. In many chronic inflammatory diseases, reduced cell death of different types of granulocytes is one important mechanism for cell accumulation. Granulocytes are constantly produced in large amounts in the bone marrow and the same numbers die, under normal circumstances, within a defined time period. Changing the rate of apoptosis rapidly changes cell numbers in such systems. Overexpression of IL-5 appears to be crucial for delaying eosinophil apoptosis in many allergic disorders, whereas overexpression of GM-CSF and G-CSF is associated with suppression of neutrophil apoptosis in bacterial and non-bacterial inflammations. Cytokine withdrawal leads to the induction of apoptosis both in vitro and in vivo. In contrast to the role of survival cytokines, little is known about the role of death factors and their receptors in the regulation of granulocyte apoptosis. Recent observations suggest a role for mitochondria in both eosinophil and neutrophil apoptosis, although the mechanisms that trigger mitochondria to release pro-apoptotic factors remain to be determined. Besides similarities, there are differences in the regulation of apoptosis between these granulocyte subtypes that include both expression and function of Bcl-2 and caspase family members. The identification of differences in the apoptosis regulation may help to define new molecular targets that allow specific induction of either eosinophil or neutrophil apoptosis by pharmacological means.

A large production of leukotrienes (LTs) can be induced in human eosinophils or neutrophils by priming with granulocyte-macrophage colony-stimulating factor and subsequent stimulation with platelet-activating factor (PAF) or the anaphylatoxin C5a. Here, we investigated the effects of a plant extract of petasites hybridus (Ze339) and its isolated active sesquiterpene ester petasin in these two in vitro cell models. Zileuton, a 5-lipoxygenase inhibitor, was used as a positive control. All compounds inhibited both cysteinyl-LT synthesis in eosinophils and LTB(4) synthesis in neutrophils. In contrast, only Ze339 and petasin, but not zileuton, abrogated PAF- and C5a-induced increases in intracellular calcium concentrations. These data suggest that Ze339 and petasin may block, compared to zileuton, earlier signalling events initiated by G protein-coupled receptors in granulocytes, perhaps at the level of or proximal to phospholipase C(beta). Taken together, petasin appears to be one major active compound of petasites hybridus extract, since it demonstrates the same inhibitory activities on calcium fluxes and subsequent LT generation in both eosinophils and neutrophils as Ze339 does.

Reactive oxygen species (ROS) and mitochondria play an important role in apoptosis induction under both physiologic and pathologic conditions. Interestingly, mitochondria are both source and target of ROS. Cytochrome c release from mitochondria, that triggers caspase activation, appears to be largely mediated by direct or indirect ROS action. On the other hand, ROS have also anti-apoptotic effects. This review focuses on the role of ROS in the regulation of apoptosis, especially in inflammatory cells.

CD137 (ILA / 4-1BB) is a member of the TNF / NGF receptor family, and has previously been suggested to be involved in T cell activation and differentiation. Here, we demonstrate that blood neutrophils from control individuals and patients with cystic fibrosis express CD137 mRNA and surface protein. In contrast, lung neutrophils derived from patients with cystic fibrosis did not express detectable CD137 levels. Such CD137-deficient neutrophils could also be generated from normal neutrophils by TNF-alpha stimulation in vitro. TNF-alpha was found to be highly expressed in epithelial cells from cystic fibrosis but not normal lungs, suggesting that TNF-alpha might account for reduced neutrophil CD137 levels under inflammatory conditions in vivo. To investigate whether CD137 is involved in the regulation of apoptosis, neutrophils were activated with functional anti-CD137 antibody in the presence or absence of different neutrophil survival factors in vitro. Activation of CD137 abrogated GM-CSF-mediated anti-apoptosis in normal but not in CD137-deficient neutrophils. Moreover, G-CSF- and IFN-gamma-mediated neutrophil anti-apoptosis was not affected by anti-CD137 antibody treatment. In conclusion, these data suggest that CD137 activation may limit GM-CSF-mediated anti-apoptosis of neutrophils. The absence of this anti-inflammatory mechanism in inflammatory responses might be associated with massive neutrophil accumulation and consequent tissue damage.

Death receptors play an important role in controlling cell numbers and immune responses. In contrast to TNF receptors, little is known about non-apoptosis functions of the Fas receptor (CD95, APO-1). Here we demonstrate that Fas receptor engagement results in the induction of the IL-10 gene in monocytes, but not in lymphocytes or dendritic cells. In contrast, TNF-alpha stimulated IL-10 production in dendritic cells but not monocytes. Fas receptor-mediated transcriptional activation of the IL-10 gene was followed by the release of large amounts of the cytokine in cell cultures and occurred in the absence of apoptosis induction. Since caspase activation did not occur in monocytes following Fas receptor engagement, it is unlikely that caspases are involved in IL-10 gene activation. Monocyte-derived IL-10 suppressed T cell proliferation induced by anti-CD3 monoclonal antibody without affecting CD3-mediated transmembrane signal transduction. In conclusion, we report about a novel pathway initiated via the Fas receptor leading to transcriptional activation of at least one cytokine gene. Fas ligand-induced IL-10 production in monocytes might represent an important anti-inflammatory mechanism in secondary immune responses.

Eosinophilic cellulitis (Wells' syndrome) is a rare disorder characterized clinically by recurrent erythematous plaques resembling cellulitis and histologically by a dermal infiltrate of lymphocytes, eosinophils and eosinophil debris between collagen bundles, forming flame figures in typical cases. A 71-year-old woman with Wells' syndrome with blood and bone marrow eosinophilia showed a good response to dapsone. The level of eosinophil cationic protein (ECP) in serum was elevated. Immunophenotyping of peripheral T cells revealed an increased proportion of CD3+CD4+T cells. The patients' cultured peripheral lymphocytes spontaneously released significant amounts of interleukin 5 (IL-5), but not interleukin 4 (IL-4) or interferon gamma (IFN gamma). These findings suggest that activated T cells may be involved in the pathogenesis of blood and tissue eosinophilia in this patient.

Apoptosis is the most common form of physiologic cell death. It is essential for organ developments during embryogenesis. After development completion, a multicellular organism must renew many lineages. For instance, red and white blood cells are constantly generated from hematopoietic progenitor cells. Therefore, physiological cell death is a necessary process to maintain correct cell numbers.

Extrakte aus den Blattern und Wurzeln der Pestwurz (Petasites hybridus L.) werden seit gut 2000 Jahren therapeutisch genutzt. Heute werden Pestwurzextrakte aufgrund ihrer spasmolytischen Wirkung vor allem bei gastrointestinalen Motilitatsstorungen, urogenitalenKoliken, Dysmenorrhoe sowie bei Asthma bronchiale und Migrane eingesetzt.

A 47 year old female with a history of hay fever and a family history of atopic eczema developed localized pruritic eczematous lesions over a three year period. The lesions became generalized within just three months. Episodes of recurrent erythroderma followed and became resistant towards any therapy. Many immediate and some delayed hypersensitivity reactions were diagnosed. In the peripheral blood, leukocytosis and hypereosinophilia were observed. In addition, levels of total IgE were highly increased in serum. Immunophenotyping of the peripheral blood T cells revealed evidence for a clonal expansion of highly activated CD4(+) T cells with reduced CD2 and CD5 surface expression. After a three-year course of severe disease, the diagnosis of a pleomorphic T cell lymphoma of the small-cell variant was established by histological examination and a polymerase-chain reaction technique to determine the rearrangements of the gamma chain of the T cell receptor. Moreover, analysis of cytokine gene expression suggested that the high IgE concentrations and eosinophil numbers observed in this patient were likely due to an increased IL-5 and IL-13 production by lymphoma T cells.

Eosinophils are potent inflammatory cells involved in allergic reactions. Recent studies suggest that delayed eosinophil apoptosis is a pathogenic event for the accumulation of these cells in chronic eosinophilic inflammation. Therefore, it is important to study the mechanisms which regulate eosinophil apoptosis. Such knowledge may help to identify useful targets for the development of new drugs. Here we review recent progress in our understanding of the processes regulating eosinophil apoptosis.

Ein multizellularer Organismus mus zur Aufrechterhaltung der zellularen Homoostase die Produktion von Zellen und deren Tod aufeinander abstimmen. Der Zelltod ist somit fur die Erneuerung von Geweben aber auch fur die Embryogenese, Metamorphose sowie fur die Entwicklung und Funktion des Immunsystems von enormer Bedeutung. Deshalb benotigt das Leben den permanent vorkommenden Zelltod. Dieser physiologisch vorkommende Zelltod ist programmiert und erfolgt oft durch Apoptose. Apoptose ist durch bestimmte morphologische Kriterien charakterisiert. Die Regulation der Apoptose kann gestort sein und dann Krankheiten verursachen. Zum Beispiel wurde eine dysregulierte Apoptose in der Pathogenese von Tumoren, Aids und autoimmunen sowie neurodegenerativen Erkrankungen beschrieben.

Development of IgE-mediated allergic conditions is dependent on the secretion of a Th2 cytokine pattern, including IL-4, IL-5, and IL-13. The induction of anergy would be one mechanism to abrogate cytokine secretion by Th2 cells, which may be pivotal to the allergic response. We demonstrate here that incubation of cloned human CD4+ phospholipase A2 (PLA)-specific Th2 cells with antigenic peptide, in the absence of professional APC, results in a state of nonresponsiveness. The anergic T cells failed to proliferate or secrete IL-4 in response to optimal stimulation with PLA and autologous, professional APC. Secretion of IL-5 and IL-13, however, was only partially inhibited. The anergic state of the Th2 cells was not associated with CD3 or CD28 down-regulation. However, anergy did appear to be closely related to alterations in signaling pathways, mediated through the TCR, of the cells. In contrast to untreated Th2 cells, anergized Th2 cells failed to respond to anti-CD3 mAb with either increased tyrosine kinase activity or increased levels of tyrosine phosphorylation of p56(lck) or ZAP70. A strong and sustained intracellular calcium flux, observed in untreated Th2 cells in response to anti-CD3 mAb, was absent in anergic Th2 cells. Furthermore, the induction of anergy seems to represent an active process, associated with increased levels of basal tyrosine kinase activity, cytokine production, and CD25 up-regulation in anergic Th2 cells. Together, our results indicate that anergy in Th2 cells is associated with defective transmembrane signaling through the TCR.

Nasal polyps, which often occur in association with allergic rhinitis and asthma, are characterized by a marked infiltration of eosinophils. Using a method for detecting eosinophils with DNA strand breaks, we found direct evidence for inhibition of eosinophil apoptosis in this model of tissue eosinophilia. By using Southern blot analysis linked to reverse transcription-PCR, we detected a mRNA signal specific for IL-5 in all nasal polyps. The identification of IL-5 as a major eosinophil survival factor was confirmed by ELISA measurements using tissue homogenates. Moreover, immunohistochemical analysis of the nasal polyp tissues demonstrated that IL-5 was localized in lymphocytes, mast cells, and eosinophils. Treatment of the eosinophil-infiltrated tissue with neutralizing anti-IL-5 mAb induced eosinophil apoptosis and decreased tissue eosinophilia. Therefore, IL-5 may represent an important cytokine responsible for the delay of the death process in eosinophils in nasal polyps. In addition, a previously suggested IL-4-dependent specific recruitment of eosinophils into the inflamed tissue could be excluded by our studies. Taken together, these findings suggest a novel mechanism by which eosinophils specifically accumulate in pathologic human tissues.

In allergic and asthmatic inflammation, activated T lymphocytes have been observed [1, 2]. A new concept to explain the preservation of the hypersensitive effector functions in these diseases has recently been introduced [3]. Inhibition of eosinophil apoptosis by T cell-derived growth factors such as granulocyte-macrophage colony-stimulating factor (GM-CSF) and interleukin-5 (IL-5) was suggested to be one reasonable explanation for the eosinophilia associated with allergy and asthma [3]. Therefore, we are interested in the biochemical and molecular mechanisms which regulate apoptosis in human eosinophils. The receptors for IL-3, IL-5, and GM-CSF share a common β subunit which does not contain an intrinsic tyrosine kinase activity, but is nevertheless essential for signal transduction. Therefore, it is important to identify the signal transduction pathways stimulated via this common β subunit which inhibit eosinophil apoptosis. We recently observed that tyrosine phosphorylation is an important mechanism to regulate apoptosis in human eosinophils [4]. In this study, we demonstrate that Lyn and Syk tyrosine kinases are involved in the anti-apoptotic pathway induced by activation of the IL-3/IL-5/GM-CSF receptor β subunit.

Physiologic cell death is a necessary process to maintain correct cell numbers. Alterations in this process may contribute to the pathogenesis of a number of human diseases. During the past few years, evidence has been adduced indicating that eosinophilic disorders are associated with a defect in eosinophil apoptosis. Here we review our recent progress in understanding the processes regulating eosinophil apoptosis, and the implications of these results for novel therapeutic possibilities.

P-Glycoprotein is a transmembrane efflux pump for different lipophilic drugs including glucocorticosteroids. Thus, upregulation of P-glycoprotein may provide a mechanism for reduced glucocorticosteroid responses as they occur in steroid-resistant asthma. To address this issue, we have examined freshly isolated peripheral blood mononuclear cells and granulocytes with regards to P-glycoprotein functional and surface expression. Using two-color immuno fluorescence techniques, we demonstrated a direct correlation between the efflux of the fluorescent dye Rh 123 and P-glycoprotein surface expression in lymphocytes, NK (natural killer) cells, monocytes and granulocytes. P-Glycoprotein levels varied widely between different leucocytes, with NK cells and CD8+ T cells having high, and granulocytes having no detectable levels. There was no evidence for upregulation of P-glycoprotein expression in any cell type from patients with steroid-resistant asthma compared to patients with steroid-sensitive or mild asthma. These results suggest that increased P-glycoprotein expression can be excluded as a mechanism for steroid resistance. Interestingly, a down regulation of P-glycoprotein expression in B cells was associated with systemic glucocorticosteroid treatment in vivo and in vitro. Whether this phenomenon may account for reduced immunoglobulin levels associated with oral glucocortico-steroid therapy remains to be determined.

Eosinophils possess the capacity to synthesize various cytokines. We demonstrate that IL-8 mRNA and protein are constitutively expressed by freshly isolated resting human eosinophils. Most of the patients with bronchial asthma or atopic dermatitis show evidence for up-regulated IL-8 protein expression in eosinophils but not in neutrophils, suggesting that an eosinophil-specific cytokine may act in these patients. To investigate whether the intracellular IL-8 can be released, eosinophils were stimulated by different cytokines and platelet-activating factor. Priming with granulocyte-macrophage CSF and a subsequent 25-min stimulation with RANTES or platelet-activating factor resulted in release of IL-8 from highly purified human eosinophils in vitro. As the eosinophil is the predominant cell in asthmatic inflammation, we determined IL-8 concentrations in bronchoalveolar lavage fluids from normal individuals and asthmatic patients. Bronchoalveolar lavage fluids from patients with bronchial asthma consistently demonstrated high IL-8 concentration compared with the controls. This suggests that IL-8 is released in vivo by inflammatory bronchial cells in asthma.

Aspirin-sensitive rhinosinusitis is a non-allergic, non-infectious perennial eosinophilic rhinitis starting in middle age and rarely seen in children. It may also been seen in atopic patients who have developed a mixed type rhinitis with recurrent airway infections. There is an intolerance to aspirin and most other NSAID. An intolerance to tartrazine, food additives, alcohol, narcotics and local anaesthetics can follow. Most aspirin-sensitive patients develop nasal polyps. Untreated, it can lead to asthma. The frequency of aspirin intolerance is 6.18% in patients with perennial rhinitis and 14.68% in patients with nasal polyps. Immunologic studies of the blood and the nasal polyps show a hyperreactive immune system with an activation of the eosinophil granulocytes due to a TH1-lymphocyte-activation. In atopic subjects with a mixed type rhinitis, we found a TH2- and B-lymphocyte-activation as well. Inhibition of eosinophil apoptosis might be a second remarkable change in the immune system of aspirin-sensitive patients. A key pathogenic event for aspirin sensitivity is the change of the leukotriene pathway for arachidonic acid metabolism releasing high amounts of leukotrienes LTC4, LTD4 and LTE4, effective chemoattractants and activators of inflammatory cells. For the diagnosis of aspirin intolerance, nasal, bronchial and oral challenge are available. The sensitivity of nasal challenge with lysine-aspirin for the diagnosis of aspirin-sensitive rhinitis is 0.93, the specificity 0.97. It is the safest test in aspirin-sensitive asthmatics causing bronchial side effects only in 0.45%. Therapy of aspirin-sensitive rhinosinusitis includes avoidance of aspirin and NSAID. A general down regulation of the immune response with glucocorticosteroids is an effective means. We prefer a maintenance dose of budesonid 400 micrograms a day. Systemic steroids for a reversibility test or in exacerbation due to viral infection are given in a dose of 50 mg a day for one week. If steroids don't work well enough, we combine them with aspirin desensitizations at a maintenance dose of 500 mg a day. Gastrointestinal side effects occur in 20% of the patients with a dose of 500 mg aspirin a day, in 46% with a mean dose of 1300 mg a day. The combined treatment of topical nasal steroids and aspirin-desensitization is effective in 65% of the patients with improvement in the symptoms of hyper-secretion, irritation and blockage, while 73% show improvement of polyps, hyposmia and anosmia. Endonasal endoscopic surgery of the ethmoids, turbinectoms and septoplasty should be done if necessary, especially in cases where conservative treatment fails. After surgery a further antiinflammatory treatment is absolutely necessary otherwise polyps reoccur in 90% of the cases after weeks or months. Unfortunately there is so far no curative treatment. New drugs like cytokine or leukotriene receptor antagonists give hope for better results in treatment of aspirin intolerance in the future.