[Morphological correlate of newborns peripheral blood cells with activity of maternal cytomegalovirus infection]

Peripheral blood cells specimens were analyzed electron microscopically in 14 newborns with congenital CMV infection (I group) and in 11 newborns with sub clinical form of CMV infection (II group) to correlate the ultra structural features of the neonates' blood cells with the maternal CMV activity in active primary and reactivated latent CMV infection forms. Control - 20 healthy newborns. The groups were arranged according the data of immune testing on IgM and IgG antibodies using ELIZA method. Criteria for cases were: 1) neonatal death and 2) severe respiratory distress or central nervous system-related symptoms at birth. In group I ultra structural findings of basophiles and lymphocytes indicate on severe damages of cells related to high risk (35%) of vertical transmission of CMV infection by placenta. In group II with relative less risk of the vertical transmission (20%) in latent reactivated CMV infection in blood cells, especially, lymphocytes, the structural changes such apoptosis and necrosis were found. The data obtained suggest the presence of significant premorbid background with subclinical course of CMV infection and structural damages of blood cells in newborns.

Histamine releasibility and expression of Lyn and Syk kinases in Indian subjects and role of less potent IL-3 in non-releaser basophils

BACKGROUND

Allergen-mediated activation of the IgE signal pathway in basophils and mast cells leads to release of mediators in-vitro and in-vivo systems. However, basophils from 10% to 20% of the population do not release histamine and other mediators on activation of the IgE signal transduction pathway and this has been attributed to the absence of tyrosine kinases Lyn and Syk. Interestingly, when these non-releaser basophils are incubated with the IL-3, it leads to the recovery of the histamine releasibility.

OBJECTIVE

To investigate histamine releasibility in the Indian population and to evaluate the role of IL-3 with reference to non-releaser phenotypes.

METHODS

Peripheral blood basophils from healthy adults were purified by density gradient centrifugation and negative immuno-selection. Histamine release assay was performed fluorometrically. Assessment of Lyn and Syk expression were carried out by flow-cytometry. SNP analysis in the IL-3 gene was carried by sequencing analysis.

RESULTS

Histamine release after ConA challenge varied greatly from 0% to 100% in Indian subjects. Eighteen percent subjects showed less than 5% histamine release (non-releasers). Flow-cytometric analysis revealed a significantly reduced expression of Lyn and Syk kinases in basophils (p<0.05). Histamine release also significantly correlated with expression of Lyn and Syk kinase (p<0.05). Non-releasers showed the presence of SNP at +79 (T-C), which leads to the one amino acid change at 8th position in the mature IL-3 from serine to proline.

CONCLUSIONS

About 18% of the Indian subjects studied showed non-releaser phenotype and also had reduced Lyn and Syk kinase expression. Non-releasers have also shown the presence of less potent isoform of IL-3/P8, which is suspected to be responsible for the non-releaser phenotype. This needs to be extended to a larger sample size and could be a potential target for the development of therapeutics for allergic patients.

Role of calcineurin in the regulation of human lung mast cell and basophil function by cyclosporine and FK506

BACKGROUND AND PURPOSE

Cyclosporine and FK506 are thought to act by targeting the Ca2+-dependent protein phosphatase, calcineurin. The aim of the present study was to determine whether cyclosporine and FK506 stabilize mast cells and basophils by interacting with calcineurin.

EXPERIMENTAL APPROACH

The effects of cyclosporine and FK506 on the IgE-mediated release of histamine from mast cells and basophils were evaluated. The presence of calcineurin in cells was determined by Western blotting. Ca2+-dependent protein phosphatase activities were assessed in cell extracts using a synthetic phosphorylated peptide that is known to serve as a substrate for calcineurin.

KEY RESULTS

FK506 was about 100-fold more potent than cyclosporine as an inhibitor of IgE-dependent histamine release from mast cells and basophils. Immunoblotting of solubilized preparations of purified cells demonstrated the presence of calcineurin in mast cells and basophils. In enzyme assays, mast cells expressed approximately 7-fold higher Ca2+-dependent protein phosphatase activity than basophils. Whereas cyclosporine effectively inhibited Ca2+-dependent protein phosphatase activity in cell extracts, FK506 was considerably less effective.

CONCLUSIONS AND IMPLICATIONS

FK506 and cyclosporine inhibit the stimulated release of histamine from mast cells and basophils. However, the ability of cyclosporine, but not FK506, to inhibit Ca2+-dependent protein phosphatase activity questions whether FK506 stabilizes mast cells and basophils by interacting with calcineurin.

Role of mast cells and basophils in chronic rhinosinusitis

Mast cells and basophils contribute to induction and/or maintenance of eosinophilic inflammation by a variety of mechanisms, including IgE-dependent and IgE-independent processes. The latter include a variety of stimuli that have only recently been elucidated, including mechanisms triggered by bacteria, virus, fungi, complement, or autoantibodies. MCs, and basophils contribute to inflammation both directly through the release of inflammatory mediators, cytokines and growth factors and indirectly through the activation of structural cells. Accumulating evidence places MCs (and most probably basophils) in a position of importance in the pathogenesis of CRS, particularly in the pathogenesis and progression of NP (Fig. 1). Mechanisms other than conventional IgE-dependent activation of MCs are intriguing as potential mechanisms of eosinophilic inflammation in non-allergic CRS/NP. Although it is not possible using current pharmacologic approaches to completely isolate the effects of MCs or basophils in CRS and NP pathogenesis, it seems most likely that such approaches will eventually be available. It might be expected that one or both of these cells will be shown to play important roles, particularly considering their potential for activation by IgE and non-IgE mechanisms, their production of a broad array of inflammatory mediators, cytokines and growth factors, and their unique assortment of proteases.

Agonist and antagonist effects of 15R-prostaglandin (PG) D2 and 11-methylene-PGD2 on human eosinophils and basophils

Prostaglandin (PG) D2 acts through both the DP(1) receptor, which is coupled to adenylyl cyclase, and the DP2 receptor (chemoattractant receptor-homologous molecule expressed on Th2 cells), which is present on eosinophils, basophils, and Th2 cells and results in cell activation and migration. The most potent prostanoid DP2 agonist so far reported is 15R-methyl-PGD2, in which the hydroxyl group has the unnatural R configuration. In contrast, the corresponding analog possessing the natural 15S configuration is approximately 75 times less potent. This raised the question of whether the isoprostane 15R-PGD2 might have potent DP2 receptor-mediated biological activity. We therefore chemically synthesized 15R-PGD2 and investigated its biological activity. This compound elicited DP2 receptor-mediated CD11b expression in human basophils and eosinophils and induced actin polymerization and migration in eosinophils with a potency about the same as that of PGD2. In contrast, it had only a weak effect on DP1 receptor-mediated adenylyl cyclase activity in human platelets. We also investigated the effects of modification of the 9-hydroxyl and 11-oxo groups of PGD2. Both PGK2, in which the 9-hydroxyl group is replaced by an oxo group, and 11-deoxy-11-methylene PGD2, in which the 11-oxo group is replaced by a CH2 group, have little or no DP1 or DP2 agonist activity. However, the 11-methylene analog is a DP2 antagonist (IC50, approximately 2 microM). We conclude that 15R-PGD2, which may be generated by oxidative stress, is a potent and selective DP2 agonist and that modification of the 11-oxo group of PGD2 can result in DP2 antagonist activity.

Trans-basement membrane migration of human basophils: role of matrix metalloproteinase-9

In allergic disorders, basophils migrate from the blood stream to inflamed tissue sites. Since trans-basement membrane migration is an important step for local basophil accumulation, we performed a human basophil transmigration assay using a model basement membrane, Matrigel. IL-3 in the upper chamber was critical for basophil trans-basement membrane migration over baseline levels, since none of the chemoattractants placed in the lower chambers induced migration. RANTES, IL-8, 5-oxo-6E,8Z,11Z,14Z-eicosatetraenoic acid (5-oxo-ETE) and platelet-activating factor (PAF) significantly up-regulated the transmigration of IL-3-treated basophils. Neutralizing experiments indicated the involvement of beta2 integrin and matrix metalloproteinase (MMP)-2/9 in basophil transmigration. Real-time quantitative PCR revealed that basophils constitutively expressed transcripts for MMP-9, and at lower levels, MMP-2, but cell-surface expression was only detected for MMP-9. MMP-9 was also detected in the cytoplasm and culture supernatant of the basophils. Treatment with IL-3 up-regulated the surface level of MMP-9 on the basophils. Our results suggest that basophils possess a unique regulatory mechanism for trans-basement membrane migration which is affected by cytokines, chemoattractants, beta2 integrin and MMPs, especially MMP-9. MMP-9 may be critically involved in the pathogenesis of local basophil influx in allergic diseases.

Effect of horse gram lectin (Dolichos biflorus agglutinin) on degranulation of mast cells and basophils of atopic subjects: identification as an allergen

Horse gram (Dolichos biflorus) is widely consumed in the tropical south Asian countries including rural areas of India. Since D. biflorus agglutinin (DBA) is an important dietary lectin in horse gram, we have studied its effect on the degranulation of mast cells and basophils of atopic subjects. Allergy to horse gram lectin has not been reported so far. Skin prick test (SPT) was performed with 100 microg/mL of DBA. DBA-specific IgE was detected by dot-blot, and ELISA. Histamine release (HR) assay was carried out using leukocytes from non-atopic and atopic subjects, and rat peritoneal exudate cells. Among the atopic group, 10 of 48 subjects (21%) were found to be positive for DBA by SPT, and none were positive in the non-atopic group (n=20). Two subjects out of the ten who tested positive for DBA by SPT were found to be sensitized to DBA as revealed by the presence of specific IgE by ELISA and dot-blot. The HR was found to be 2- to 3-fold higher in DBA-allergic subjects than in non-atopic and atopic subjects. Basophil HR by DBA was found to be similar in both non-atopic and atopic subjects. However, DBA induces activation of mast cells in vivo in a sub-population (21%) of atopic subjects. Two subjects have been identified as having food allergy to horse gram based on the presence of DBA-specific IgE with a positive correlation to basophil HR. This is the first report of food allergy to horse gram, and DBA has been identified as an allergen.

Effect of sodium sulfite on mast cell degranulation and oxidant stress

BACKGROUND

Sulfur dioxide is 1 of 6 environmental pollutants monitored by the Environmental Protection Agency. Its ability to induce bronchoconstriction is well documented. It is highly soluble, initially forming sulfite ions in solution. Sulfur oxides are important constituents of other pollutants, such as diesel exhaust and fine particulates.

OBJECTIVE

To investigate the cellular responses of sulfite on cultured mast cells (rat basophilic leukemia [RBL-2H3] cells) and human peripheral blood basophils.

METHODS

Sulfite-induced mast cell degranulation and intracellular production of reactive oxygen species were evaluated in the presence and absence of antioxidants and inhibitors of redox metabolism. Degranulation was determined using beta-hexosaminidase, serotonin, and histamine release assays. Induction of intracellular reactive oxygen species generation was determined using the redox-sensitive dye 2',7'-dichlorofluorescein diacetate.

RESULTS

Sodium sulfite induced degranulation and the generation of intracellular reactive oxygen species in RBL-2H3 cells. These responses were inhibited by the free radical scavenger tetramethylthiourea and the flavoenzyme inhibitor diphenyliodinium but not by depletion of extracellular calcium. Peripheral blood basophils also showed histamine release after exposure to sodium sulfite

CONCLUSIONS

Sulfite, the aqueous ion of sulfur dioxide, induces cellular activation, leading to degranulation in mast cells through a non-IgE-dependent pathway. The response also differs from IgE-mediated degranulation in that it is insensitive to the influx of extracellular calcium. The putative pathway seems to rely on activation of the reduced form of nicotinamide adenine dinucleotide phosphate oxidase complex, leading to intracellular oxidative stress.

Role of chemokines in severe asthma

The severe asthma phenotype is exhibited by a subset of asthma patients whose asthma symptom is poorly controlled by current therapies. Severe asthma represents a high unmet medical need and warrants research into the mechanisms driving the underlying pathophysiology. It is hypothesized that the underlying pathology associated with severe asthma is driving the symptoms experienced by these patients, which may share common features with mild to moderate asthma or may represent a unique pathological phenotype. For the purpose of this review, the pathophysiology associated with asthma in general are described and extended to incorporate severe asthma. Chemokines may contribute towards multiple features of asthma pathophysiology and this current review focuses on the biology of chemokines pertaining to asthma pathophysiology. Chemokines are important recruiters and activators of inflammatory cells and these infiltrating cells interact with resident cells, such as fibroblasts and it is through these pathways that chemokines appear to exert multiple biological actions. Clinical trials are underway with therapeutics targeting chemokine pathways for other inflammatory diseases. It is hoped that the information generated from these studies will contribute towards furthering our understanding of chemokine biology and be applied towards targeting severe asthma.

Evaluation of basophil activation in food allergy: present and future applications

PURPOSE OF REVIEW

The diagnosis of immediate hypersensitivity relies on specific IgE and history. Because of low specificity, however, provocation challenges are often necessary. Furthermore, IgE testing does not predict features such as reaction severity; nor can it discriminate cross-reactivity from multiple sensitizations. Direct and passive basophil activation tests may address these needs. In addition, measuring basophil activation ex vivo may be useful for monitoring patients with food allergies.

RECENT FINDINGS

Several papers using basophil activation tests demonstrate comparable sensitivity and specificity to current testing for food allergy. Flow-based basophil activation tests have also been used to assess functional characteristics of patient IgE. Finally, several activation phenotypes have been identified as markers of allergic inflammation in vivo; these phenotypes appear to correspond to earlier reports of spontaneous histamine-releasing basophils in patients with active allergic inflammation.

SUMMARY

Although in their early stages, direct basophil activation tests may prove to be useful in the clinic. Indirect basophil activation studies are useful when applied to compare functional aspects of IgE. Identification of basophil activation ex vivo is a promising approach for monitoring allergic inflammation.

Effects of Cellular Fine Structure on Scattered Light Pattern

Biological cells are complex in both morphological and biochemical structure. The effects of cellular fine structure on light scattered from cells are studied by employing a three-dimensional code named AETHER which solves the full set of Maxwell equations by using the finite-difference time-domain method. It is shown that changes in cellular fine structure can cause significant changes in the scattered light pattern over particular scattering angles. These changes potentially provide the possibility for distinguishability of cellular intrastructures. The effects that features of different intrastructure have on scattered light are discussed from the viewpoint of diagnosing cellular fine structure. Finally, we discuss scattered light patterns for lymphocyte-like cells and basophil-like cells.

Mechanisms of action of anti-immunoglobulin E therapy

The currently approved anti-immunoglobulin E (IgE) agent omalizumab is a humanized monoclonal antibody that recognizes human IgE in the vicinity of its binding sites for high- and low-affinity IgE receptors. Omalizumab binds free IgE and the complexes that are formed are removed by the hepatic reticuloendothelial system. Over time, IgE comes off its receptors on various cells (primarily basophils and mast cells), rendering these cells "nonfunctional," in that they lose their ability to respond to allergen. This process is enhanced by the fact that, as IgE receptors are freed, their numbers on cell surfaces decline. The kinetics of cellular defunctionalization may differ depending on the cell type (basophils are believed to lose IgE earlier), the number of cell-surface-specific IgE molecules before initiation of treatment, and the cellular sensitivity of individual patients. Inability to respond to allergen reduces acute allergic reactions and their inflammatory and physiological consequences such as late reductions in lung function and tissue eosinophilia. Chronic airway inflammation is suppressed also, but the effect on airway hyperresponsiveness is modest. A potential role of anti-IgE therapy to act as an immunomodulator by affecting antigen presentation through the removal of IgE from the surface of dendritic cells has not been explored. Also unknown is whether anti-IgE can bind to membrane-bound IgE on B lymphocytes and influence IgE production by these cells. Anti-IgE therapy has provided a strong proof of concept for the central role of the IgE system in asthma and other allergic diseases. (Allergy Asthma

Germin-like protein Cit s 1 and profilin Cit s 2 are major allergens in orange (Citrus sinensis) fruits

Oranges are clinically relevant allergenic foods. To date, orange allergens have not been characterized in detail. The study is aimed at analyzing the sensitization profile in orange-sensitized subjects with and without clinical allergy, and to identify orange allergens. Fifty-six sensitized subjects with self-reported reactions to orange were grouped into reactors (anaphylaxis or multiple episodes of immediate reactions and/or positive challenge tests) and non-reactors (negative open food challenge tests). Allergens were characterized by IgE immunoblotting, N-terminal sequencing, IgE-inhibition assays, and mediator release assays were performed to determine the allergenic potency of orange profilin. Of 56 subjects, 23 were classified as orange allergic showing mainly an oral allergy syndrome. Of 23 subjects classified as orange allergic, 22 were sensitized to profilin, Cit s 2. In patients with mono-sensitization to profilin in vitro histamine releases up to 75% from basophils were induced using orange extract and purified plant profilins. Of the allergic patients 78% were sensitized to germin-like protein, Cit s 1. Both allergens showed retained IgE reactivity in heat-processed orange juice. Interestingly, subjects with and without clinical allergy showed a comparable sensitization profile. Profilin and germin-like proteins are major orange allergens. The potential clinical relevance of orange profilin was indicated by its strong capacity to release histamine from basophils. However, a predominant sensitization to both allergens in subjects without symptoms also indicates a high frequency of clinically insignificant sensitization.

5. IgE, mast cells, basophils, and eosinophils

IgE, mast cells, basophils, and eosinophils constitute essential elements in allergic inflammation. Allergen-specific IgE, synthesized in response to allergens in the environment, becomes fixed to FcepsilonRI on the membranes of mast cells and basophils. Aggregation of receptor-bound IgE molecules on re-exposure to specific allergen results in the production of mediators that produce the allergic response. Principal among the cells drawn to sites of mediator release is the eosinophil.

Signaling transduction pathways involved in basophil adhesion and histamine release

BACKGROUND

Little is known about basophil with respect to the different signaling transduction pathways involved in spontaneous, cytokine or anti-IgE induced adhesion and how this compares to IgE-dependent and IgE-independent mediator secretion. The purpose of the present study was to investigate the roles of beta1 and beta2 integrins in basophil adhesion as well as hosphatidylinositol 3-kinase (PI3K), src-kinases and extracellular signal regulated kinase (ERK) 1/2 in basophil adhesion and histamine release (HR).

METHODS

Basophils (purity of 10% - 50%) were preincubated with anti-CD29 or anti-CD18 blocking antibodies before used for adhesion study. Basophils were preincubated with the pharmacological inhibitors wortmannin, PP1, PD98059 before used for adhesion and HR study. Cell adherence to bovine serum albumin (BSA) or fibronectin (Fn) was monitored using cell associated histamine as a basophil marker and the histamine was measured by the glass fiber assay.

RESULTS

Basophil spontaneous adhesion to Fn was inhibited by anti-CD29. Interleukin (IL)-3, granulocyte/macrophage colony stimulating factor (GM-CSF) induced adhesion to BSA was inhibited by anti-CD18. Wortmannin at 1 micromol/L and PP1 at 20 micromol/L strongly interfered with, whereas PD98059 at 50 micromol/L weakly inhibited basophil spontaneous adhesion to Fn. One micromol/L wortmannin strongly inhibited IL-3, IL-5, GM-CSF and anti-IgE induced adhesion to BSA. PP1 at 20 micromol/L partly inhibited anti-IgE induced adhesion. Fifty micromol/L PD98059 marginally inhibited IL-5, weakly inhibited anti-IgE, partly inhibited GM-CSF induced adhesion. Wortmannin, PP1 and PD98059 inhibited anti-IgE (1:100 or 1:1000) induced basophil HR in a dose dependent manner. They inhibited calcium ionophore A23187 (10 micromol/L, 5 micromol/L) induced basophil HR in a dose dependent manner, but to different extend with PP1 being the most efficient.

CONCLUSIONS

Basophil spontaneous adhesion to Fn is mediated by beta1-integrins whereas cytokine induced adhesion to BSA is mediated by beta2-integrins. PI3K, src-kinases and ERK1/2 play distinct signaling roles in basophil adhesion and HR. PI3K is the key player while ERK1/2 is the weakest participant.

Recent advances in the use of genetically engineered negative signaling molecules to treat allergic diseases

PURPOSE OF REVIEW

This review summarizes current knowledge regarding the control of human mast cell and basophil signaling and recent developments using a new therapeutic platform consisting of a human bifunctional gamma and epsilon heavy chain (Fcgamma-Fcepsilon) protein to inhibit allergic reactivity.

RECENT FINDINGS

Crosslinking of FcgammaRIIb to FcepsilonRI on human mast cells and basophils by a genetically engineered Fcgamma-Fcepsilon protein (GE2) leads to the inhibition of mediator release upon FcepsilonRI challenge. GE2 protein was shown to inhibit cord blood-derived mast cell and peripheral blood basophil mediator release in vitro in a dose dependent fashion including inhibition of human IgE reactivity to cat. In addition, IgE-mediated release from lung tissue was inhibited through GE2. The mechanism of inhibition in mast cells included alterations in IgE-mediated Ca2+ mobilization, Syk phosphorylation and the formation of Dok-Grb2-SHIP complex. Proallergic effects of Langerhans-like dendritic cells and B cell IgE switching were also inhibited by GE2. In vivo, GE2 was shown to block passive cutaneous anaphylaxis (PCA) driven by human IgE in mice expressing the human FcepsilonRI and inhibit skin test reactivity to dust mite antigen in a dose dependent manner in rhesus monkeys. The balance between positive and negative signaling controls mast cell and basophil reactivity that is critical in the expression of human allergic diseases. This approach using a human Fcgamma-Fcepsilon fusion protein to co-aggregate FcepsilonRI with the FcgammaRII holds promise as a new therapeutic platform for the immunomodulation of allergic diseases and potentially other mast cell/basophil-dependent disease states.

5-Oxo-6,8,11,14-eicosatetraenoic acid is a potent chemoattractant for human basophils

BACKGROUND

5-Oxo-6,8,11,14-eicosatetraenoic acid (5-oxo-ETE) is a chemoattractant for eosinophils and neutrophils, and the messenger RNA for its receptor, the oxo-eicosatetraenoic acid receptor (OXE), has been detected in several tissues.

OBJECTIVES

This study aimed at clarifying the role of 5-oxo-ETE in the regulation of basophil function.

METHODS

Basophil responses were determined in assays of flow-cytometric shape change, Ca(2+) flux, chemotaxis, and histamine release. Messenger RNA for OXE was detected by real-time PCR.

RESULTS

We observed that human eosinophils were 3 to 10 times more sensitive to 5-oxo-ETE than neutrophils in flow-cytometric shape change and Ca(2+) flux assays, as estimated from the half-maximal responses of the cells. Basophils responded to 5-oxo-ETE in the shape change assay with a sensitivity similar to that of eosinophils. 5-Oxo-ETE was a weak inducer of Ca(2+) flux in basophils and did not cause histamine release but was a highly effective chemoattractant for basophils in the low nanomolar concentration range in a pertussis toxin-sensitive manner. In agreement with these functional studies, the messenger RNA for the 5-oxo-ETE receptor, OXE, was detectable in basophils as in monocytes, eosinophils, and neutrophils, but not in fibroblasts. Specimens from sinus mucosa, tonsils, and adenoids also contained detectable levels of messenger RNA for OXE.

CONCLUSION

Our data suggest that 5-oxo-ETE is potentially involved in the regulation of basophil recruitment and might hence be a useful therapeutic target in atopic disease.

Stem cell factor stimulates the chemotaxis, integrin upregulation, and survival of human basophils

BACKGROUND

Little is known about the mechanisms that regulate the selective recruitment of basophils to sites of allergic inflammation.

OBJECTIVE

Here we examine the role of stem cell factor (SCF) in the regulation of basophil function.

METHODS

Human basophils were isolated from peripheral blood, and their migration was investigated in chemotaxis assays. Apoptosis was detected by means of annexin V and propidium iodide staining. The expression of cell-surface molecules was measured by means of flow cytometry.

RESULTS

SCF amplified the chemotactic responsiveness of human peripheral blood basophils to the chemoattractants eotaxin, monocyte chemotactic protein 2 and macrophage inflammatory protein 1alpha, and C5a, without being chemotactic or chemokinetic by itself. SCF synergized with chemoattractants in causing basophil upregulation of the integrin CD11b, and this effect was inhibited by a c-kit antibody, the tyrosine kinase inhibitor imatinib mesylate (STI-571), and a phosphatidylinositol 3 kinase inhibitor but not by inhibitors of p38 mitogen-activated protein kinase or mitogen-activated protein kinase/extracellular signal-regulated kinase kinase. Basophils bound fluorescence-labeled SCF and expressed its receptor, c-kit, which was markedly upregulated in culture for 24 to 48 hours in the presence of IL-3. Moreover, SCF prolonged basophil survival in concert with IL-3 by delaying apoptosis. These effects of SCF were selective for basophils because chemotaxis and CD11b upregulation of eosinophils or neutrophils were unchanged.

CONCLUSION

SCF might be an important selective modulator of basophil function through a phosphatidylinositol 3 kinase-dependent pathway.

Nerve growth factor influences IgE-mediated human basophil activation: functional properties and intracellular mechanisms compared with IL-3

NGF and IL-3 play a unique role in supporting human basophil differentiation and mediator secretion. Their importance in allergic disease is underlined further by studies showing elevated levels of these factors in asthmatics. Here, we compared the abilities of IL-3 and NGF to stimulate basophil histamine, IL-4 or IL-13 release, either directly or in conjunction with IgE-dependent stimulation and assessed the intracellular signals responsible. Our results show that the ability of IL-3 and NGF to enhance IgE-dependent histamine release are similar. Both factors also potentiated IgE-dependent IL-13 secretion to a greater degree than the release of histamine or IL-4. At high concentrations (100 ng/ml), IL-3 and NGF alone were capable of releasing cytokines but little histamine. These abilities of IL-3 and NGF to modulate basophil activation were sensitive to blockade by specific inhibitors of PI 3-kinase, p38 MAPK and PLC, but not PKC, suggesting that their effects are mediated considerably by pathways comparable to IgE-dependent signalling.