Cutaneous late-phase response to allergen. Mediator release and inflammatory cell infiltration

A kinetic study in adults with food hypersensitivity assessed as eosinophil activation in fecal samples

BACKGROUND

Immune-mediated food hypersensitivity affecting the gut is difficult to evaluate, and objective tools to diagnose local gastrointestinal (GI) inflammatory reactions are lacking.

OBJECTIVES

To determine whether allergic manifestations in adults with a history of food-related GI symptoms could be assessed in feces during symptomatic and non-symptomatic periods, using the surrogate markers, eosinophil cationic protein (ECP), eosinophil protein X (EPX) and myeloperoxidase (MPO).

METHODS

Thirteen subjects with food hypersensitivity-related GI symptoms, confirmed by a positive double-blind placebo-controlled food challenge (DBPCFC), were subjected to an open kinetic food challenge design for 6 weeks. Symptoms were recorded and scored during the 3-week study period and stool samples were obtained every day. The surrogate markers ECP, EPX and MPO were measured in the supernatants from feces samples.

RESULTS

A significant increase in abdominal pain, distension and flatulence was observed during challenge, with a gradual decrease during elimination diet. Both between days and subjects, EPX levels were more frequently increased compared to ECP and MPO. Individuals with a history of a short duration of symptoms had significantly higher mean levels of EPX and MPO than those with a longer duration of symptoms.

CONCLUSIONS

An overall increase in levels of eosinophil markers, in particular EPX, was observed in feces from patients with food-related GI symptoms. However, rather than being a tool to differentiate symptomatic from non-symptomatic periods, EPX might be used for detecting an ongoing clinical or subclinical chronic inflammation, that may have an impact on the patient's clinical course of GI symptoms.

The second PGD(2) receptor CRTH2: structure, properties, and functions in leukocytes

Prostaglandin (PG) D(2) plays a broad range of physiological and pathophysiological functions. Until just a few years ago, it was thought that most of the biological actions of PGD(2) are mediated via the classical PGD(2) receptor DP. Recently, we identified a second PGD(2) receptor, chemoattractant receptor-homologous molecule expressed on T helper (Th)2 cells (CRTH2), with different functions relative to DP. Here, we review the recent findings on the structure, tissue distribution, ligand selectivity, signalling pathways, and functions in leukocytes of this receptor. The data suggest that the PGD(2)/CRTH2 system play important roles in allergic inflammation through its stimulatory effects on Th2 cells, eosinophils, and basophils.

Functional and morphologic characterization of eosinophils in the lower intestinal mucosa of patients with food allergy

OBJECTIVE

The aim of this study was to characterize the functional and morphologic features of eosinophils in the intestinal mucosa of patients with food allergy.

METHODS

Eighteen patients with food allergy and 11 controls took part in this study. In every patient, corresponding biopsy samples obtained during colonoscopy were quantitatively assessed by immunohistochemical methods (EPO-I) and subjected to mucosa oxygenation using eosinophilic cationic protein (ECP). Initial basal release, spontaneous and anti-IgE-dependent release, and the total ECP content of mucosal biopsies were studied.

RESULTS

Morphologically, mucosal eosinophils in patients with food allergy have distinct features, occur in larger amounts, and show a distinct distribution pattern (i.e., intraepithelial, lamina propria, and submucosa). Their initial basal release is similar to that of controls, but stimulation of the IgE receptor with anti-IgE results in 40-fold activation (p < 0.001). In food allergy patients, the density of eosinophils, the presence of intraepithelial eosinophils, and the rate of degranulation showed a highly significant correlation to the initial basal release of ECP by mucosal tissue (Kendall tau = 0.619, 0.381, and 0.609, respectively; p < 0.05 for all) but not to their capability to be stimulated with anti-IgE.

CONCLUSIONS

Eosinophils of the lower intestine of patients with food allergy show characteristic features with regard to morphology, distribution, and functional behavior to IgE receptor stimulation. Immunostaining of eosinophil peroxidase (EPO) detects important characteristic features that are missed with conventional hematoxylin-eosin staining.

The release of basogranulin in response to IgE-dependent and IgE-independent stimuli: validity of basogranulin measurement as an indicator of basophil activation

BACKGROUND

Basogranulin, the novel basophil granule protein recognized by the monoclonal antibody BB1, can be released by stimulation with anti-IgE antibody or calcium ionophore. However, the kinetics and regulation of its secretion are unknown.

OBJECTIVE

We quantified basogranulin and histamine release in response to a range of stimuli to assess whether basogranulin secretion is a reliable marker of basophil activation.

METHODS

Isolated peripheral blood basophils were stimulated with anti-IgE antibody, calcium ionophore, N -formyl-Met-Leu-Phe, and complement C5a. The released basogranulin and histamine were quantified by dot blotting with BB1 and a fluorometric method, respectively. Basogranulin localization was confirmed by flow cytometry.

RESULTS

Both basogranulin and histamine displayed a bell-shaped response curve when basophils were challenged with anti-IgE. Half-maximal release occurred within 30 seconds. Basogranulin levels were maximal by 15 minutes, whereas those for histamine continued increasing to 30 minutes. Wortmannin, a PI3-K inhibitor, suppressed the release of both mediators. Basophils from donors with the "nonreleaser" phenotype secreted neither mediator in response to anti-IgE. Non-IgE-dependent stimuli released both mediators in parallel in a concentration-dependent manner. The correlation between the relative amounts of each mediator released was highly significant (r =.901, P <.0001, n = 87). Flow cytometry revealed that some of the secreted basogranulin adhered to the cell surface.

CONCLUSIONS

Basogranulin is secreted along with histamine in response to both FcepsilonR I-related and unrelated stimuli. It is therefore a valid marker of basophil activation and could provide the basis for an immunoassay that distinguishes between basophil and mast cell activation.

8-Methoxypsoralen and long-wave ultraviolet A inhibit the release of proinflammatory mediators and cytokines from human Fc epsilon RI+ cells: an in vitro study

The in vitro effects of 8-MOP (concentrations of 20, 100 and 500 ng/ml) alone or in combination with UVA on mediator release from human basophils and skin mast cells (HSMC), activated with immunological and non-immunological stimuli, were investigated. With respect to basophils activated with anti-IgE serum, the results of this study show that: (i) 8-MOP alone inhibits histamine, LTC(4), IL-4 and IL-13 release concentration dependently with a maximal effect at 500 ng/ml (a concentration not reached in vivo); and (ii) UVA irradiation (5 J/cm(2)), after 8-MOP incubation, enhances this inhibitory effect on all released mediators, but for IL-4 and IL-13 the percentage inhibition is also significant for the 8-MOP concentrations (20-100 ng/ml) employed in vivo during PUVA treatment. Moreover, histamine release from basophils activated with non-immunological stimuli (FMLP and A23187) is inhibited by 8-MOP, alone or in combination with UVA. With respect to the HSMC activated with anti-IgE serum, the results show that: (i) 8-MOP alone reduces histamine release concentration dependently; and (ii) this inhibitory effect is enhanced by UVA irradiation (5 J/cm(2)). Histamine release from HSMC activated with A23187 is not modified either by 8-MOP alone or by 8-MOP plus UVA.

Blood basophil numbers in chronic ordinary urticaria and healthy controls: diurnal variation, influence of loratadine and prednisolone and relationship to disease activity

BACKGROUND

The basopenia of chronic urticaria relates to histamine releasing autoantibodies in the serum of patients with autoimmune urticaria. This reduction in circulating basophils may be due to active recruitment into weals. If so, it might be expected that numbers in blood would be reduced when urticaria is active and increased after treatment. The primary aim of this study was to look at diurnal variation of basophil numbers in patients with chronic ordinary urticaria (not physical or vasculitic) in relation to disease activity and the effect of treatment with antihistamines and corticosteroids, and to compare the results with healthy controls. A secondary aim was to compare a standard manual counting method with automated basophil counts and to look at numbers of other circulating leucocytes that might be relevant to urticaria pathogenesis.

METHODS

Manual basophil counts using a toluidine blue stain and automated 5-part differentials (Coulter Gen. S) were performed at 4-hourly intervals from 08.00 to 20.00 in 10 healthy controls (six women, age 24 to 63 years) and seven chronic urticaria patients (five women, 24 to 50 years). All chronic urticaria patients had severe daily or almost daily urticaria. Only one of six chronic urticaria sera showed in vitro basophil histamine releasing activity. Counts were performed without treatment, after a week of taking loratadine 10 mg daily and after 3 days of adding prednisolone at 0.6 mg/kg/day (maximum 40 mg). Daily urticarial activity scores (UAS) were derived from weal numbers and itch, maximum 7.

RESULTS

There was no significant overall diurnal variation of basophil numbers in healthy controls or chronic urticaria patients. Mean (SE) manually counted basophil were higher in healthy controls than chronic urticaria (43.4/ microL (2.1) vs. 4.4 (0.8), P < 0.001). Basophil counts were reduced in healthy controls on steroids (19.2 (1.9), P < 0.001) but increased in chronic urticaria (8.9 (1.9), P < 0.001). Loratadine did not influence them. UAS fell on treatment (3.3 (0.4) baseline, 1.4 (0.5) on loratadine and 0.5 (0.2) on prednisolone with loratadine, P < 0.001). There was a negative linear correlation between basophil numbers and UAS in untreated chronic urticaria patients (P = 0.001, Spearman rank correlation). Manual and automated basophil counts showed poor agreement. Lymphocyte numbers were lower in chronic urticaria than healthy controls. Neutrophils increased whereas lymphocytes and eosinophils decreased in all subjects on prednisolone. They were unaffected by loratadine.

CONCLUSION

The results are consistent with the hypothesis that circulating basophils may be recruited from blood into urticarial weals during disease activity. Automated counts are not suitable for assessing basophil numbers in chronic urticaria. The relevance of reduced lymphocyte numbers in chronic urticaria needs to be explored.

Inhibition of allergic dermal inflammation by the novel imidazopyridazine derivative TAK-427 in a guinea pig experimental model of eczema

Antigen challenge by patch ovalbumin emulsion induced an eczema-like skin lesion in epicutaneously sensitized guinea pigs. Diseased skin sites were macroscopically characterized by manifestations of dermatitis, such as erythema, edema, and papules, and microscopically characterized by acanthosis, spongiosis, and dermal infiltration by eosinophils. Using such lesions as a model of eczema, we evaluated the potential value of TAK-427 [2-[6-[[3-[4-(diphenylmethoxy)piperidino]propyl]amino] imidazo[1,2-b]pyridazin-2-yl]-2-methylpropionic acid dihydrate] as a therapeutic agent for atopic dermatitis by comparing it with dexamethasone and antihistamines. TAK-427 (0.3-30 mg/kg, p.o.) and dexamethasone (3 and 10 mg/kg, p.o.) inhibited eosinophil infiltration into the skin and ameliorated the dermatitis manifestations and epidermal damage. By contrast, none of the antihistamines tested (azelastine, ketotifen, terfenadine, and cetirizine) suppressed the eosinophil infiltration or dermatitis manifestations. To elucidate the mechanism by which TAK-427 inhibited the development of eczema, we investigated cytokine expression in the affected skin. Both TAK-427 and dexamethasone suppressed the increased mRNA expression of interleukin (IL)-13, granulocyte-macrophage colony-stimulating factor, IL-1alpha, tumor necrosis factor-alpha, interferon-gamma, and IL-8, but not IL-10, suggesting that TAK-427 inhibits allergic inflammation of the skin leading to the development of eczema by inhibiting the expression of proinflammatory cytokines after antigen challenge.

Activation markers of human basophils: CD69 expression is strongly and preferentially induced by IL-3

BACKGROUND

The biological functions of basophils are precisely regulated by various cytokines in vitro, but little is known about surface markers that are upregulated during the cytokine-mediated activation process.

OBJECTIVE

It has been well established that CD69, CD44, and CD54 represent "activation markers" for cytokine-mediated eosinophil activation. The objective of this study was to elucidate the expression and regulation of these molecules in human basophils in vitro as well as in vivo.

METHODS

Basophils were purified from venous blood by means of density gradient centrifugation followed by negative selection. Surface expression was analyzed by means of flow cytometry. We also studied the expression of CD69, CD44, and CD54 on basophils in bronchoalveolar lavage fluid and blood specimens from patients with asthma.

RESULTS

CD44 and CD54 were constitutively expressed on basophils and moderately upregulated by IL-3. On the other hand, CD69 expression was only weakly observed in freshly isolated basophils, but IL-3 induced extremely high levels of expression. Surface CD69 appeared rather slowly in comparison with CD63 and CD11b, and the induction of expression was completed within 24 hours. Basophil CD69 had no functional relevance, but it did have biological relevance. Whole blood basophils from asthmatic individuals expressed significantly higher levels of CD69 than did those from normal individuals. Furthermore, bronchoalveolar lavage fluid basophils showed higher levels of CD69 expression than did blood basophils from the same donors.

CONCLUSION

CD69 expression on basophils was preferentially and strongly upregulated by IL-3. CD69 on basophils might be useful as an in vitro as well as in vivo marker of activation of these cells by IL-3.

Chronic urticaria

Chronic urticaria has a spectrum of clinical presentations and causes. About 50% of patients with "idiopathic" disease have histamine-releasing autoantibodies in their blood. The term autoimmune urticaria is increasingly being accepted for this subgroup of patients, in whom immunosuppressive therapies may be appropriate if conventional approaches to management are unsuccessful. This article reviews the classification, causes, and management of chronic urticaria in light of recent advances in the understanding of its etiology.

LEARNING OBJECTIVE

At the conclusion of this learning activity, participants should have up-to-date knowledge of the classification, assessment, and management of chronic urticaria and understand where the concept of autoimmune urticaria fits into existing frameworks.

Increased expression of endothelial cell adhesion molecules due to mediator release from human foreskin mast cells stimulated by autoantibodies in chronic urticaria sera

Histamine-releasing antibodies that act against the epitope of the alpha chain of Fc(epsilon)RI (anti-Fc(epsilon)RI(alpha) antibody) that may affect pathogenesis in serum of patients with chronic urticaria. We assessed the capability of anti-Fc(epsilon)RI(alpha) antibody in sera from patients with chronic urticaria to release histamine and cytokines, and to induce the expression of endothelial cell adhesion molecules. We also assessed the release of inflammatory mediators from cultured foreskin mast cells, and expression of endothelial cell adhesion molecules on human dermal microvascular endothelial cells. Cells were pretreated with mast cell-conditioned media: culture media of mast cells treated with sera from chronic urticaria patients containing anti-Fc(epsilon)RI(alpha) antibody. Histamine release from human foreskin mast cells challenged with sera, increased after both 20 min and 16 h intervals. Leukotriene D4 release also increased at both 20 min and 16 h. Tumor necrosis factor-alpha increased significantly in foreskin mast cell culture challenged with sera of chronic urticaria patients. After the stimulation of human dermal microvascular endothelial cells with the conditioned media, the expression of intercellular cell adhesion molecule-1, vascular cell adhesion molecule-1, and E-selectin increased significantly. Treatment of the conditioned media with anti-tumor necrosis factor-alpha monoclonal antibody partially inhibited the expression of intercellular cell adhesion molecule-1, vascular cell adhesion molecule-1, and E-selectin. The data suggest that sera from patients with chronic urticaria containing anti-Fc(epsilon)RI(alpha) antibody release mediators and tumor necrosis factor-alpha by activating human foreskin mast cells. This release can play a pathogenic role in chronic urticaria by activating endothelial cells, in part due to the actions of tumor necrosis factor-alpha from mast cells.

Basophils in airway disease

The inflammatory response that is often associated with asthma is characterized by the recruitment of eosinophils, basophils, and lymphocytes. Until recently, profiling the basophil and defining its functional characteristics have been difficult. With the advent of some new tools, there is a steadily increasing body of information on the presence and potential activities of the basophil. Although the precise role of these cells in airway diseases, such as asthma, remain unclear, relatively accurate enumeration is now possible. Coupled with new insights into cytokine secretion from these cells, a more accurate picture of the dynamics of this specialized form of inflammation is available for refining our hypotheses regarding its regulation.

Basophils in chronic urticaria

Blood basophils are reduced in chronic urticaria and respond less well to immunologic stimuli. Active recruitment of basophils from peripheral blood into lesional skin may be important in wheal pathogenesis.

The ACVD task force on canine atopic dermatitis (VI): IgE-induced immediate and late-phase reactions, two inflammatory sequences at sites of intradermal allergen injections

Intradermal testing is a common diagnostic procedure used in the evaluation of dogs with suspected atopic dermatitis (AD). To do this, most investigators assess the appearance of wheals that develop at the sites of intradermal allergen injections. However, wheals are rarely seen in dogs with naturally occurring AD. Furthermore, infiltration of inflammatory cells into the injection sites can occur 6-24h later, a phenomenon known as the late-phase reaction. The histological appearance of these late-phase reactions closely approximates that seen in the natural disease, suggesting that they might be more relevant than the immediate reactions. In this paper, we review the literature on immediate and late-phase reactions and re-assess the evidence for using current intradermal testing procedures as a diagnostic test in dogs.

Immunohistochemical detection of human basophils in postmortem cases of fatal asthma

The role of human basophils in bronchial asthma has been hard to define. In this study, we used the basophil-specific monoclonal antibody (mAb), 2D7, in postmortem lung sections from individuals who die in status asthmaticus (fatal asthma [FA]) to determine if the pathology of FA is associated with an increase in basophil numbers in the lung. As controls, we used lung sections of patients who had a history of asthma but died from nonasthmatic causes (nonfatal asthma [NFA]) as well as patients with no history of asthma (control [C]). In lung sections from all three groups, basophils were scattered throughout the large and small airways, airway epithelium, submucosa, and alveolar walls. The numbers of basophils in the lungs of patients with FA ranged from 41 to 119 cells/mm(2), significantly more than the numbers of basophils in lungs from individuals with a history of asthma (NFA; 0 to 16 cells/ mm(2)) and in the control lungs (C; 0 to 13 cells/mm(2)). In contrast, CD45-positive cells were not significantly different in the airways of FA and NFA, although there were significant increases in the two groups compared with control subjects. In summary, basophil infiltration was significantly increased in lungs from individuals who died from asthma, supporting the hypothesis that basophils are involved in the pathogenesis of FA.

Cetirizine inhibits skin reactions but not mediator release in immediate and developing late-phase allergic cutaneous reactions. A double-blind, placebo-controlled study

BACKGROUND

Recent reports have indicated cetirizine, a potent H(1)-receptor antagonist, to possess a number of anti-inflammatory effects, e.g. inhibition of mast cell degranulation and inhibition of leucocyte migration and activation.

OBJECTIVE

The aim of this study was to compare the effects of cetirizine on skin responses and mediator release in intact skin in immediate and developing late-phase allergic reactions by microdialysis technique.

METHODS

Cetirizine 10 mg once daily or matching placebo were administered to 10 atopic subjects for 6 days followed by a 2-week washout in a randomized, double-blind, placebo-controlled, cross-over trial. Immediate skin test responses to allergen, codeine, and histamine and late-phase reactions to allergen were assessed. The time course of extracellular levels of inflammatory mediators in intact skin were monitored by microdialysis techniques using 2 kDa and 3 MDa cut-off fibers, respectively.

RESULTS

Cetirizine significantly reduced immediate weal and flare reactions to allergen, codeine, and histamine. Injection of allergen, but not buffer controls, induced a significant release of histamine, tryptase, prostaglandin D(2), total protein, and eosinophilic cationic protein. No significant increase of leukotriene B(4) and myeloperoxidase was observed. Cetirizine inhibited early total protein extravasation by 40%, but this did not reach a significant level. None of the inflammatory mediators were significantly inhibited by cetirizine. Cetirizine significantly reduced the late-phase skin induration to allergen by approximately 30%.

CONCLUSION

Cetirizine potently reduced skin responses in immediate allergic reactions without inhibition of early mediators. These data indicate cetirizine to be a potent H1-receptor antagonist with no effect on mast cell activation. It did not inhibit any of the late-phase mediators, but it reduced the late skin reaction. These data suggest that mediators other than those actually measured may play a significant role in the clinical late-phase reaction.

Glucocorticoids induce basophil apoptosis

BACKGROUND

Induction of apoptosis represents an important mechanism by which glucocorticoids (GCCs) exert their anti-inflammatory properties. The effects of GCCs on apoptosis have been determined in various immune cells and found to vary among different cell types. On the other hand, the effects of GCCs on apoptosis of basophils, active participants in allergic inflammation, have remained obscure.

OBJECTIVE

The objective of this study was to investigate the effects of GCCs on basophil apoptosis.

METHODS

Basophils were highly purified (purity, >97%) by Percoll density gradient centrifugation followed by negative selection. Cell status was determined by their ability to bind annexin V and exclude propidium iodide. DNA fragmentation was determined by flow cytometry.

RESULTS

Dexamethasone (DEX) significantly accelerated the decrease in live cells and increased the number of apoptotic cells in a time-dependent fashion. Light microscopy as well as DNA fragmentation assay confirmed the induction of apoptosis by DEX. A half-maximal effect was observed in a DEX concentration range from 10(-9) to 10(-8) mol/L. Sex steroids did not induce basophil apoptosis at all. DEX also induced basophil apoptosis in the presence of low doses of IL-3.

CONCLUSION

GCCs exert potent apoptogenic effects on basophils. GCC-mediated apoptogenic effects on basophils might have implications with respect to the mechanism of action of this class of drugs in allergic disorders.

Chronic urticaria: background, evaluation, and treatment

Urticaria and angioedema will affect 15% of the general population during their lifetime, and this remains one of the most vexing cutaneous conditions to evaluate and treat. Patients frequently go from one physician to another in hopes of finding a healthcare provider who can identify the cause and cure the ailment. Physicians treating hives are equally frustrated as they ponder the utility of obtaining a panel of screening laboratory tests that have previously been shown to have a low yield or obtaining selected allergy tests in a group of patients who are no more prone to allergic disease than the general public. This review presents recent information in a clinical context with the aim of aiding the physician in understanding the pathophysiology of urticaria and formulating an intelligent evaluation and treatment plan.

Food hypersensitivity and irritable bowel syndrome

Irritable bowel syndrome is a common condition but its pathophysiology remains poorly understood. Many irritable bowel syndrome patients give a history of food intolerance, but data from dietary elimination and re-challenge studies are inconclusive. Multiple aetio-pathological mechanisms have been postulated. The gut has an extensive immune system but current understanding of processing of food antigens in health and disease is limited. There is no clinically useful marker available to test for food hypersensitivity in irritable bowel syndrome. Researchers have employed both skin tests and serum immunoglobulins (IgG and IgE) as markers of food hypersensitivity in various disorders including irritable bowel syndrome, but published data are equivocal. In this article, the evidence for the role of food hypersensitivity in irritable bowel syndrome is reviewed and, based on the available data, a possible pathophysiological hypothesis has been formulated.

Mucosal pathophysiology and inflammatory changes in the late phase of the intestinal allergic reaction in the rat

Relatively little information exists concerning the late phase of the allergic reaction in the gastrointestinal tract. Here, we characterized jejunal mucosal pathophysiology and inflammation after oral antigen challenge of sensitized rats, and examined the role of mast cells in events after challenge. Sprague-Dawley rats, mast cell-deficient (Ws/Ws), and +/+ control rats were sensitized to horseradish peroxidase, and challenged intragastrically with antigen 14 days later. Jejunal segments were obtained at 0.5 to 72 hours after challenge for functional assessment in Ussing chambers and for morphological assessment by light and electron microscopy. Intestine from sensitized Sprague-Dawley rats demonstrated enhanced ion secretion and permeability at all times after challenge. Electron microscopy revealed abnormal mitochondria within enterocytes and disruption of the epithelial basement membrane associated with influx into the mucosa of mast cells, eosinophils, neutrophils, and mononuclear cells. Many inflammatory cells appeared activated. In contrast, antigen-challenged Ws/Ws rats demonstrated no functional changes or inflammatory cell infiltrate. We conclude that oral antigen challenge of sensitized rats induces sustained epithelial dysfunction. Mast cells mediate both epithelial pathophysiology and recruitment of additional inflammatory cells that may contribute to persistent pathophysiology and symptoms.

Characterization of the inflammatory infiltrate during IgE-mediated late phase reactions in the skin of normal and atopic dogs

In canine and human atopic patients, the intracutaneous injection of offending allergens is followed by the development of both immediate and late-phase reactions. The present study was performed to expand on the characterization and dynamics of inflammatory cell subsets during IgE-mediated late-phase reactions in canine skin. Three normal dogs and three Dermatophagoides farinae-allergic dogs were selected for this experiment. All dogs were challenged intradermally with mite allergen, purified anticanine IgE antibodies (positive control) or phosphate-buffered saline (negative control). Skin biopsies were obtained before and 6, 12 and 24 h post-injection. Sections were stained with metachromatic and eosinophil-specific histological stains. Additionally, we used an immunohistochemical method with antibodies specific for canine leukocyte antigens. This study confirmed the occurrence of a late-phase reaction in atopic skin following allergen challenge, and in normal and atopic canine skin after intradermal injection of IgE-specific antibodies. Whereas early emigrating dermal cells were composed chiefly of neutrophil and activated eosinophil granulocytes, there was an influx of alpha beta T-lymphocytes and dermal dendritic cells in later stages of the late-phase reactions. Because IgE-mediated late-phase reactions resemble spontaneous atopic canine skin lesions, both at macroscopic and microscopic levels, we propose the use of similar challenges to study the anti-inflammatory effects of anti-allergic drugs in a pre-clinical setting.

IL-4 production by human basophils found in the lung following segmental allergen challenge

BACKGROUND

Human blood basophils secrete high levels of IL-4 following activation with specific allergen, yet their role as cytokine-producing cells in allergic lesions has not been described.

OBJECTIVE

Our objective was to investigate whether and under what conditions basophils infiltrating allergic lesions in the lung secrete IL-4 in vitro.

METHODS

Bronchoalveolar lavage (BAL) cells were recovered 20 hours after segmental allergen challenge. Basophils were enriched with Percoll using a protocol commonly used for blood basophils. IL-4 and histamine were measured in culture supernatants following activation with a variety of stimuli. Two-color flow cytometry was performed to detect intracellular IL-4.

RESULTS

IL-4 protein was detected in all basophil culture supernatants following a 4- to 5-hour incubation in medium alone; the levels obtained did not significantly increase with the addition of anti-IgE. BAL basophils failed to release histamine in response to specific allergen but showed nearly 60% histamine release with N-formyl-methionyl-leucyl-phenylalanine, suggesting that they were desensitized to IgE-mediated stimuli as a result of their activation in vivo. Using these same conditions, IL-4 was not detected in BAL cell fractions enriched for lymphocytes and eosinophils. Ionomycin induced IL-4 secretion by BAL basophils, and this response was reduced with the addition of phorbol myristate acetate. In contrast, phorbol myristate acetate promoted the secretion of IL-4 by BAL cells enriched for lymphocytes; both findings are identical to those reported for basophils and lymphocytes purified from blood. Flow cytometry confirmed the secretion of IL-4 by BAL basophils.

CONCLUSIONS

These data suggest that basophils migrating to the lung following allergen challenge represent a major source of IL-4.

Prostaglandin D2 selectively induces chemotaxis in T helper type 2 cells, eosinophils, and basophils via seven-transmembrane receptor CRTH2

Prostaglandin (PG)D2, which has long been implicated in allergic diseases, is currently considered to elicit its biological actions through the DP receptor (DP). Involvement of DP in the formation of allergic asthma was recently demonstrated with DP-deficient mice. However, proinflammatory functions of PGD2 cannot be explained by DP alone. We show here that a seven-transmembrane receptor, CRTH2, which is preferentially expressed in T helper type 2 (Th2) cells, eosinophils, and basophils in humans, serves as the novel receptor for PGD2. In response to PGD2, CRTH2 induces intracellular Ca2+mobilization and chemotaxis in Th2 cells in a Galphai-dependent manner. In addition, CRTH2, but not DP, mediates PGD2-dependent cell migration of blood eosinophils and basophils. Thus, PGD2 is likely involved in multiple aspects of allergic inflammation through its dual receptor systems, DP and CRTH2.

Calreticulin is an interleukin-3-sensitive calcium-binding protein in human basophil leukocytes

BACKGROUND

IL-3 enhances basophil histamine release upon stimulation with any known secretagogue. The molecular mechanism behind this regulation is not known, although some observations suggest that IL-3 modulates the calcium part of the signal transduction mechanism. The inhibitory action of glucocorticoids on basophils can be reversed by stimulation with IL-3.

METHODS

Calcium-binding proteins in the basophil cell line KU812 were identified by two-dimensional gel electrophoresis, Calcium-overlay assay, N-terminal sequence analysis, and mass spectometry. The presence of the same proteins in purified human basophil leukocytes was established by comigration of KU812 and human basophil proteins on the two-dimensional gels. The expression of the calcium-binding proteins in the absence and presence of IL-3 and/or anti-IgE was determined by densitometric measurement of the spots on the two-dimensional gels.

RESULTS

Calreticulin was identified on the two-dimensional gel of KU812 proteins. A protein with exactly the same migration pattern was found on the gels of proteins from purified human basophils. Immunoblotting with a specific antihuman calreticulin antibody confirmed that this protein was calreticulin. Subsequent analysis showed that the expression of calreticulin in the basophils is upregulated twofold upon stimulation with rhIL-3, even in doses below those needed for enhancement of histamine release.

CONCLUSIONS

The expression of calreticulin in human basophil leukocytes is regulated by IL-3. Calreticulin is known to modulate IP3-dependent Ca2+ influx in different cell systems, and calreticulin overexpression inhibits steroid-induced transcriptional activation. Therefore, modulation of calreticulin expression may be one mechanism by which IL-3 exerts its effects on human basophils.

Role of selectins on IgE-mediated skin reaction

Selectins play an important role on leukocytes infiltration into inflammatory tissues. To understand the role of selectins, we investigated the effects of selectin-IgG chimeras and anti selectin antibodies on the murine IgE-mediated skin inflammation model. Biphasic skin reactions were induced by intradermal challenge with ovalbumin (OA) to ears of actively sensitized mice. This reaction was characterized by immediate and late phase responses observed as which were induced via a rapid increase in capillary permeability and leukocyte infiltration, respectively. The expression of E-selectin mRNA was significantly increased to reach its highest level at 2 h after OA challenge. E-, P-, and L-selectin-IgG chimeras inhibited the late phase responses, i.e. ear swelling, neutrophil infiltration and eosinophil infiltration at 24 h after OA challenge in a dose-dependent manner at dose range of 0.1 - 10 mg kg(-1), i.v. Antiselectin antibodies did not inhibit the increase of ear swelling. But anti E- and P-selectin antibodies significantly inhibited neutrophil infiltration and eosinophil infiltration. These results indicate that selectins play an important role on the late phase response of the murine IgE-mediated skin inflammation model by mediating inflammatory cell adhesion to endothelium.

Expression and function of P-selectin glycoprotein ligand 1 (CD162) on human basophils

BACKGROUND

The endothelial cell adhesion molecule P-selectin may contribute to selective leukocyte migration in allergic diseases by binding to its ligand, P-selectin glycoprotein ligand 1 (PSGL-1), on eosinophils and other leukocytes. Although expression of PSGL-1 on basophils has been detected in leukocyte typing workshops, its function on basophils has not been explored.

OBJECTIVE

We sought to characterize the expression and function of PSGL-1 on human basophils and a basophil-like cell line (KU812) and to compare these characteristics with those for PSGL-1 on eosinophils and neutrophils.

METHODS

Basophils, eosinophils, and neutrophils were enriched from peripheral blood by using density gradient centrifugation and immunomagnetic negative selection. KU812 cells were cultured by using standard techniques. Indirect immunofluorescence and flow cytometry were used to determine surface PSGL-1 expression under various conditions, and Western blotting was used to analyze the molecular forms of PSGL-1 on each cell type. Static adhesion assays were performed by using immobilized recombinant P-selectin and relevant blocking antibodies. Histamine release assays were done by using adherent and nonadherent basophils to determine whether adhesion by means of PSGL-1 altered basophil releasability.

RESULTS

The expression of PSGL-1 on basophils was similar to that on neutrophils but was approximately 30% less bright than levels on eosinophils. Levels on basophils were 10-fold higher than on KU812 cells. Basophil activation by means of IgE cross-linking resulted in reductions in surface expression of PSGL-1 and L-selectin, as well as increased CD11b expression. Western blot analysis of PSGL-1 revealed that the molecular weights of the bands for neutrophils and basophils were similar, whereas those for eosinophils were of greater molecular weights. Static adhesion assays demonstrated that basophils bound well to P-selectin, whereas KU812 cells bound poorly. Adhesion of basophils to P-selectin was completely blocked by antibodies to either P-selectin or PSGL-1. Finally, adhesion to P-selectin did not alter the magnitude or kinetics of anti-IgE-induced histamine release.

CONCLUSION

Expression of PSGL-1 on basophils is more similar to that on neutrophils than that on eosinophils. KU812 cells express much lower levels of this molecule but, like basophils and other cells, bind to P-selectin by means of PSGL-1. P-selectin expression at sites of allergic inflammation is likely to play an important role in human basophil recruitment, but adhesion by means of PSGL-1 does not alter IgE-dependent basophil histamine release.

Systemic activation of basophils and eosinophils: markers and consequences

Basophils and eosinophils are important effector cells in human allergic diseases; they play a significant role in promoting allergic inflammation through the release of proinflammatory mediators (such as histamine, leukotriene C(4), major basic protein, eosinophil cationic protein, IL-4, and IL-13, among others). Notably, in allergic subjects, these cells exist in higher numbers and in a more activated state compared with nonatopic control subjects. Evidence for the greater activation state includes increased expression of intracellular and surface markers and hyperreleasability of allergy mediators. We have been interested in the phenotypic markers of effector-cell activation for many years. There is considerable overlap among activation markers, and few activation markers have been found that define a unique phenotype that is quantifiable in the assessment of the presence and severity of allergic disease. This review summarizes the existing evidence for systemic activation of human basophils and eosinophils in allergic diseases. The potential mechanisms responsible for functional and morphologic alterations in these effector cells and the specificity and utility of surface markers in the assessment of allergic disease activity or severity are also discussed.

Modulation of the atopy patch test reaction by topical corticosteroids and tar

BACKGROUND

Pharmacologic studies in atopic eczema (AE) are difficult to standardize. Patients with AE differ in the stage of their skin disease (acute, subacute, chronic).

OBJECTIVE

This study was designed to assess macroscopic and microscopic effects of pretreatment with topical glucocortico-steroids (GCSs) and tar on the atopy patch test (APT) reaction in patients with atopic eczema.

METHODS

Nonlesional skin of the back of patients with AE (n = 6) was treated for 3 weeks at 3 different sites with triamcin-olonacetonide 0.1% in cetamacrogol ointment (GCSs), pix liquida 10% in cetamacrogol ointment (tar), and cetamacrogol ointment (vehicle), respectively. APTs were performed, and biopsy specimens were taken from all these sites (time = 0 and 24 hours) for immunohistochemical analysis.

RESULTS

Treatment with both GCSs and tar was able to reduce the macroscopic outcome of the APT reaction. Furthermore, both treatment modalities had an almost equally inhibiting effect on the influx of T cells, eosinophils, and CD1(+), RFD1(+), IFN-gamma(+), and IL-4(+) cells, as well as on the percentage of vessels expressing the adhesion molecules vascular cell adhesion molecule 1 and E-selectin in response to epicutaneous aeroallergen challenge.

CONCLUSION

Although both treatments significantly reduced the various cellular constituents of allergic inflammation, all cell types remained present. In addition, this study shows that the APT can be used to evaluate the effect of topical anti-inflammatory treatments on allergic inflammation in patients with AE.

Role of mast cells in the onset of IgE-mediated late-phase cutaneous response in mice

BACKGROUND

In mice that are passively sensitized to IgE, cutaneous antigen challenge produces a biphasic response with peaks at 1 and 24 hours after challenge.

OBJECTIVE

We investigated the role of mast cells in the IgE-mediated late-phase reaction in mice.

METHODS

We histologically and ultrastructurally investigated the morphologic changes of mast cells during the biphasic responses.

RESULTS

Degranulation of mast cells, which was observed between 4 and 24 hours after challenge, reached a peak at 8 hours. Piecemeal degranulation was seen during the immediate phase reaction. The number of IL-6-positive mast cells was increased after 4 hours in both IgE-sensitized and unsensitized mice, but positive cells showed a greater increase in sensitized mice and reached a peak after 8 hours. With in situ hybridization experiments, mast cells were positive for IL-6 messenger RNA at 6 hours after challenge.

CONCLUSION

These findings indicate that anaphylactic degranulation of mast cells and the expression of IL-6 mRNA within 4 hours after antigen challenge are important for the onset of the late-phase allergic cutaneous reaction in mice.

Temporal patterns of mediator release during developing cutaneous late-phase reactions

BACKGROUND

Several inflammatory mediators have been found released in sites of cutaneous late phase reactions (LPR). However, the temporal pattern of their release during LPR development has not been characterized.

OBJECTIVE

Determine hourly accumulation of mediator release in comparison with gross and inflammatory cell responses during developing LPR.

METHODS

Skin chamber appended to sites of allergen and diluent control challenge with hourly collections. Then, study of exuding leucocytes in chamber bases.

RESULTS

In the allergen-challenged sites, histamine release peaked in the first hour, then low level release over the next 5 h. Lactoferrin release from neutrophils started by the second hour, likely associated with released IL-8. Eosinophil cationic protein levels started increasing slightly later. The percentage of exuding leucocytes which were activated was significantly higher in the allergen challenge sites than in the control challenge sites

CONCLUSIONS

Both gross LPR and local inflammatory cell responses in the skin start soon after the immediate mast cell activation in IgE-mediated responses. Such inflammatory responses include leucocyte activation and mediator release.

Cutting edge: differential production of prostaglandin D2 by human helper T cell subsets

Several effector molecules, including cytokines, are differentially produced by Th1 and Th2 cells. We used a gene expression screen method to identify a gene encoding hematopoietic PG D synthase (hPGDS) which was preferentially expressed in human Th2 but not Th1 clones. Studies with anti-hPGDS mAbs confirmed the Th2-dominated expression of hPGDS protein. Upon stimulation with anti-CD3 plus anti-CD28 mAbs, coordinated cyclooxygenase-2 expression and PGD2 production were induced in Th2 lines. hPGDS expression was also observed in a small population (<1.0%) of peripheral blood CD4+ lymphocytes from healthy adults. Most hPGDS-expressing CD4+ lymphocytes showed a typical Th2-type cytokine pattern. Our results suggest that, at the sites of Ag presentation, at least part of the Th2 cell population produces PGD2, which may be involved in various aspects of Th2-related immune responses similar to mast cells.

Basophils, eosinophils, and mast cells in atopic and nonatopic asthma and in late-phase allergic reactions in the lung and skin

BACKGROUND

Previous studies used indirect methods to identify basophils in the bronchi in asthma, and the numbers were not compared with eosinophils and mast cells. Furthermore, differences in basophil numbers between atopic and nonatopic asthma at baseline and between late-phase skin and asthmatic reactions have not been previously documented.

OBJECTIVE

The basophil granule-specific mAb BB1 was used to identify basophils in (1) bronchial biopsy specimens from atopic asthmatic subjects and nonatopic asthmatic subjects and control subjects, (2) biopsy specimens from atopic asthmatic subjects before and after inhalational allergen challenge, and (3) late-phase skin reactions. Basophil numbers were compared with EG2(+) eosinophils and tryptase(+) mast cells.

METHODS

Cells were enumerated in bronchial and skin biopsy specimens by means of immunohistochemistry with the alkaline phosphatase-antialkaline phosphatase method.

RESULTS

There were elevated numbers of basophils in baseline biopsy specimens in atopic asthmatic subjects compared with atopic control subjects or normal control subjects, although eosinophils and mast cells were 10-fold higher. There was an intermediate number of basophils in nonatopic asthmatic subjects. Basophils increased after allergen inhalation, but again basophils were less than 10% of eosinophils. In contrast, basophils in cutaneous late-phase reactions were approximately 40% of infiltrating eosinophils. The peak of basophil accumulation was at 24 hours, whereas maximal eosinophil infiltration occurred at 6 hours. One third of cutaneous basophils had morphologic appearances suggestive of degranulation.

CONCLUSION

Numerous basophils infiltrated cutaneous late-phase reactions in atopic subjects. However, this cell was not prominent in bronchial biopsy specimens of asthmatic subjects, either at baseline or after allergen challenge.

CRTH2, an orphan receptor of T-helper-2-cells, is expressed on basophils and eosinophils and responds to mast cell-derived factor(s)

We have recently cloned a putative chemoattractant receptor, named CRTH2, which is preferentially expressed on human T-helper- (Th) 2 but not Th1 cells. In this study, we demonstrated that CRTH2 is also highly expressed on peripheral blood basophils and eosinophils. Our search for a CRTH2 ligand identified mast cells as the possible producers of a ligand. When stimulated with an anti-FcepsilonR1 antibody, cord blood-derived mast cells secreted factor(s) that induced Ca(2+) mobilization in CRTH2-expressing K562 cells but not in mock transfected cells. These findings implied the involvement of CRTH2 in mast cell-mediated immune responses such as allergic reactions.

Frequency and characterization of antigen-specific IL-4- and IL-13- producing basophils and T cells in peripheral blood of healthy and asthmatic subjects

BACKGROUND

Both basophils and T cells are known to secrete IL-4 and IL-13 after activation with either nonspecific stimuli or specific antigen, but the relative contribution of these 2 cell types to overall cytokine production is unclear.

OBJECTIVES

To further characterize basophil cytokine production and compare it with that of T cells, we examined the frequency of IL-4- and IL-13-producing basophils and T cells in human PBMCs by means of flow cytometry after activation in allergic asthmatic and normal subjects.

METHODS

PBMCs obtained from whole blood after Percoll gradient were activated with specific antigen or ionomycin and fixed. PBMCs were made permeable; stained with antibodies to IgE, CD3, and either IL-4 or IL-13; and analyzed by means of flow cytometry.

RESULTS

Preformed cytokines were not detected in unactivated basophils. After ionomycin activation, 60% to 90% of basophils from both control and allergic asthmatic subjects expressed IL-4 and IL-13. Specific antigen induced cytokine expression by 10% to 20% of basophils from the asthmatic group only. After specific antigen activation, basophils accounted for 4 times more IL-4-producing cells than did T cells. IL-4 and IL-13 production at 2 hours was exclusively from basophils. After allergen activation, CD40 ligand was upregulated on a subset of peripheral blood basophils.

CONCLUSIONS

These data demonstrate that basophils are the predominant peripheral blood cells that express IL-4 and IL-13 in the first 6 hours after antigen activation and strengthen the putative role of basophils both in IgE production and in the generation of allergic inflammation.

Experimental models of skin inflammation

The skin is the most accessible organ of the body in which to view the inflammatory process and its pharmacological modulation. However, there are relatively few studies in which the response of the dermal vasculature to inflammatory stimuli has been assessed quantitatively or the chemical mediators of the response measured directly. The mechanisms underlying these responses remain unclear despite the fact that altered microvascular function plays an important part in a number of clinical conditions. This paper describes recent studies in which an experimental model of inflammation in the skin has been used to investigate the pharmacological mechanisms underlying microvascular responses. As allergen-induced cutaneous weal and flare responses are mediated mainly by histamine, we first set out to characterize the vascular responses using the intradermal injection of histamine as a first step, experimental model of allergic skin disease. To quantify the inflammatory responses and to explore the mediator mechanisms underlying them we have combined the techniques of scanning laser Doppler imaging of blood flux and dermal microdialysis to make simultaneous measurements of changes in skin blood flow and the release of mediators within the weal and flare response to intradermal injection of histamine in human skin, in vivo.

Chemical mediators in atopic dermatitis: involvement of leukotriene B4 released by a type I allergic reaction in the pathogenesis of atopic dermatitis

BACKGROUND

The mediators produced from a type I allergic reaction have not yet been able to explain the pathogenesis of atopic dermatitis (AD).

OBJECTIVE

The purpose of this study was to elucidate the involvement of leukotriene (LT) B4 produced from a type I allergic reaction in the pathogenesis of AD.

METHOD

The release of LTB4 was measured both in vitro, in passively sensitized and antigen-challenged human skin slices, as well as in vivo, in skin chambers on patients with AD.

RESULTS

LTB4 was released from in vitro human skin by stimulation of the antigen (54.9 +/- 14.6 pg/g wet weight of skin by antigen challenge and 28.0 +/- 11.1 pg/g in control skin, P <.002). Antigen-specific release of LTB4 and histamine was also observed in vivo in nonlesional skin from the patients with AD by using the skin chamber technique.

CONCLUSION

LTB4 release during type I allergic reaction in human skin has been determined in vitro. The released LTB4 possibly contributes to cellular response at the acute inflammatory lesion of AD.

Extracellular Signal-Regulated Kinases Regulate Leukotriene C4 Generation, But Not Histamine Release or IL-4 Production from Human Basophils

Human basophils secrete histamine and leukotriene C4 (LTC4) in response to various stimuli, such as Ag and the bacterial product, FMLP. IgE-mediated stimulation also results in IL-4 secretion. However, the mechanisms of these three classes of secretion are unknown in human basophils. The activation of extracellular signal-regulated kinases (ERKs; ERK-1 and ERK-2) during IgE- and FMLP-mediated stimulation of human basophils was examined. Following FMLP stimulation, histamine release preceded phosphorylation of ERKs, whereas phosphorylation of cytosolic phospholipase A2 (cPLA2), and arachidonic acid (AA) and LTC4 release followed phosphorylation of ERKs. The phosphorylation of ERKs was transient, decreasing to baseline levels after 15 min. PD98059 (MEK inhibitor) inhibited the phosphorylation of ERKs and cPLA2 without inhibition of several other tyrosine phosphorylation events, including phosphorylation of p38 MAPK. PD98059 also inhibited LTC4 generation (IC50 = ∼2 μM), but not histamine release. Stimulation with anti-IgE Ab resulted in the phosphorylation of ERKs, which was kinetically similar to both histamine and LTC4 release and decreased toward resting levels by 30 min. Similar to FMLP, PD98059 inhibited anti-IgE-mediated LTC4 release (IC50, ∼2 μM), with only a modest effect on histamine release and IL-4 production at higher concentrations. Taken together, these results suggest that ERKs might selectively regulate the pathway leading to LTC4 generation by phosphorylating cPLA2, but not histamine release or IL-4 production, in human basophils.

The late asthmatic response is associated with baseline allergen-specific proliferative responsiveness of peripheral T lymphocytes in vitro and serum interleukin-5

BACKGROUND

Increasing insights into the mechanism underlying the allergen-induced late asthmatic response (LAR) have been gained with implication of activated eosinophils and CD4+ T lymphocytes. However, the patient characteristics that indicate the individual capacity to develop a LAR are not well-defined.

METHODS

In 22 subjects with mild to moderate house dust mite-allergic asthma, we investigated the relationship between the LAR and two other models of late-phase allergic inflammation, i.e. the allergen-specific proliferative response of peripheral blood T lymphocytes in vitro and the late cutaneous response. Non-specific bronchial responsiveness (PC20histamine), lung function (FEV1), peripheral blood eosinophil count, early phase allergic skin sensitivity, and levels of total and specific immunoglobulin E (IgE) were determined prior to bronchial allergen challenge. Serum levels of interleukin-5 (IL-5) were measured before and at several time points after allergen inhalation.

RESULTS

A significant correlation was found between the magnitude of the LAR and the allergen-specific proliferative response of peripheral T lymphocytes (r = 0.44, P = 0.04) but not the late cutaneous response. Stepwise-multiple linear regression of the magnitude of the LAR on the parameters analysed at baseline, resulted in a model combining PC20 histamine, early phase allergic skin sensitivity, and the allergen-specific proliferative response of peripheral T lymphocytes (R2 = 0.84, P<0.001). No contribution of the late cutaneous response to the prediction of the LAR was found. Serum levels of IL-5 increased significantly at 6 h (P = 0.01) and 24 h (P = 0.003) after bronchial allergen challenge and correlated with the allergen-specific proliferative response of peripheral T lymphocytes in vitro (rho = 0.48, P = 0.02).

CONCLUSIONS

The findings in this study point to a role of TH2-lymphocyte responses in the development of the allergen-induced LAR. In allergic asthmatic patients, allergen-specific responsiveness of peripheral T-lymphocytes in vitro may serve as a model to determine the individual capacity to develop a LAR after allergen inhalation.

Granulocyte-macrophage colony-stimulating factor and interleukin-3 cause basophil histamine release by a common pathway: downregulation by sodium

Granulocyte-macrophage colony-stimulating factor (GM-CSF) and interleukin-3 (IL-3) are recognized as enhancers, but not as inducers, of histamine release from normal human basophils. However, when extracellular Na+ is removed IL-3 acquires the capacity to induce histamine release. The aim of this study was to evaluate whether GM-CSF can induce basophil histamine release using the same pathway of IL-3. Leucocyte suspensions from normal human subjects were stimulated with GM-CSF, IL-3 and anti-IgE, and histamine release was evaluated by an automated fluorometric method. In a physiological medium, GM-CSF (10 ng/ml) and IL-3 (10 ng/ml) did not provoke histamine release, in spite of an efficient response to anti-IgE (10 micrograms/ml). However, when extracellular Na+ was substituted iso-osmotically with N-methyl-d-glucamine+ or with choline+, GM-CSF and IL-3 were able to trigger histamine release from either mixed leucocyte suspensions or purified human basophils. The effect of GM-CSF on basophil histamine release was dose dependent, with optimal release at a dose of 1 ng/ml after incubation at 37 degrees for 60-120 min. The kinetics of IL-3-induced histamine release were similar, whereas anti-IgE-induced histamine release was more rapid, being almost maximal after incubation for 30 min. A good correlation was found between GM-CSF-induced and IL-3-induced histamine release; furthermore, the combined effects of the two cytokines were less than additive, suggesting that they share the same pathways leading to histamine release. When extracellular Na+ concentration was increased from 0 to 140 mm, histamine release induced by GM-CSF, IL-3 and anti-IgE was reduced progressively. In contrast, histamine release induced by these stimuli was upregulated when the concentration of extracellular Ca2+ was increased. These results provide indirect evidence that GM-CSF and IL-3 can induce basophil histamine release by a common pathway that is downregulated by Na+.

Expression of Protein Kinase C Isozymes in Human Basophils: Regulation by Physiological and Nonphysiological Stimuli

The expression of protein kinase C (PKC) isozymes in human basophils and the regulation of PKC isozymes during basophil activation by phorbol 12-myristate 13-acetate (PMA) ± ionomycin, f-met-leu-phe (FMLP), and anti-IgE antibody were examined. In human basophils (> 98% purity), PKCβΙ, βΙΙ, δ, and  were expressed, PKC was difficult to detect, and PKCγ and η were undetectable. In unstimulated basophils, PKCβI and βII were found primarily in the cytosol fraction (95% ± 3% of total and 98% ± 1%, respectively). Within 5 minutes of stimulation with PMA (100 ng/mL), both PKCβI and βII were translocated to the membrane fraction (85% ± 4% and 83% ± 6%, respectively). In resting cells, 48% ± 3% and 61% ± 10% of PKCδ and , respectively, existed in the membrane fraction. Within 1 minute of stimulation with PMA, 90% ± 6% of PKC was found in the membrane fraction, however, no translocation of PKCδ was apparent. Stimulation with FMLP caused modest translocation (≈20%) of all PKC isozymes by 1 minute, whereas stimulation with anti-IgE antibody led to no detectable changes in PKC location throughout a 15-minute period of measurement. However, concentrations of PMA and ionomycin that alone caused no PKC translocation and little histamine release, together caused significant histamine release but no apparent PKC translocation. Studies with bis-indolylmaleimide analogs showed inhibition of PMA-induced, but not anti–IgE-induced, histamine release. These pharmacological studies suggest that PKC does not play a prodegranulatory role in human basophil IgE-mediated secretion.

© 1998 by The American Society of Hematology.

Expression of Protein Kinase C Isozymes in Human Basophils: Regulation by Physiological and Nonphysiological Stimuli

The expression of protein kinase C (PKC) isozymes in human basophils and the regulation of PKC isozymes during basophil activation by phorbol 12-myristate 13-acetate (PMA) ± ionomycin, f-met-leu-phe (FMLP), and anti-IgE antibody were examined. In human basophils (&gt; 98% purity), PKCβΙ, βΙΙ, δ, and  were expressed, PKC was difficult to detect, and PKCγ and η were undetectable. In unstimulated basophils, PKCβI and βII were found primarily in the cytosol fraction (95% ± 3% of total and 98% ± 1%, respectively). Within 5 minutes of stimulation with PMA (100 ng/mL), both PKCβI and βII were translocated to the membrane fraction (85% ± 4% and 83% ± 6%, respectively). In resting cells, 48% ± 3% and 61% ± 10% of PKCδ and , respectively, existed in the membrane fraction. Within 1 minute of stimulation with PMA, 90% ± 6% of PKC was found in the membrane fraction, however, no translocation of PKCδ was apparent. Stimulation with FMLP caused modest translocation (≈20%) of all PKC isozymes by 1 minute, whereas stimulation with anti-IgE antibody led to no detectable changes in PKC location throughout a 15-minute period of measurement. However, concentrations of PMA and ionomycin that alone caused no PKC translocation and little histamine release, together caused significant histamine release but no apparent PKC translocation. Studies with bis-indolylmaleimide analogs showed inhibition of PMA-induced, but not anti–IgE-induced, histamine release. These pharmacological studies suggest that PKC does not play a prodegranulatory role in human basophil IgE-mediated secretion.

© 1998 by The American Society of Hematology.

Identification of a basophil leukocyte interleukin-3-regulated protein that is identical to IgE-dependent histamine-releasing factor

This study aimed to identify basophil leukocyte proteins associated with interleukin (IL)-3 and/or anti-IgE activation by two-dimensional (2-D) gel electrophoresis. We noticed one particular protein showing increased synthesis after recombinant human (rh)IL-3 and, to a lesser extent, anti-IgE stimulation. The protein was also present in the culture medium in increased amounts after rhIL-3 stimulation. On the basis of comigration with proteins in published 2-D gel electrophoresis databases and immunoblotting with a specific monoclonal antibody, we identified this protein as translationally controlled tumor protein (TCTP), also known as p23 or IgE-dependent histamine-releasing factor. The antibody was shown to be specific for TCTP/IgE-dependent histamine-releasing factor by blotting on 2-D gels of proteins from human lymphocytes and the human basophilic cell line KU812, followed by N-terminal amino-acid sequencing of the bound protein. Densitometric analysis of the gels showed that the synthesis of IgE-dependent histamine-releasing factor in human basophil leukocytes was dose dependent upon rhIL-3 stimulation with an optimum of 100 ng/ml. The level of the protein in the medium was also highest at an optimal rhIL-3 concentration of 100 ng/ml. Supernatants from cultured basophils were able to stimulate histamine release from other basophils. This histamine release was decreased by precipitation of TCTP/IgE-dependent histamine-releasing factor from these supernatants.

Comparison of inflammatory events during developing immunoglobulin E-mediated late-phase reactions and delayed-hypersensitivity reactions

To compare cellular and mediator responses in early developing late-phase skin reactions (LPR) and delayed-hypersensitivity (DH) reactions in the same subjects, responses in skin chambers overlying sites of challenge with pollen antigen and Candida albicans antigens were compared in six humans with demonstrated prominent LPR and DH responses. Histamine levels in overlying chamber fluids at 1 h were much higher at LPR than at DH sites (P = 0.002). After the next 4 h, leukocyte exudation was higher at LPR than at DH sites (P = 0.005). Most leukocytes were activated neutrophils with greater frequency of superoxide-secreting cells and released lactoferrin at LPR than at DH sites (P = 0.01 and P = 0.02, respectively). The frequency of exuding eosinophils was higher, but not significantly so (P = 0.5), at LPR sites. Although significantly more eosinophils at LPR sites were activated (P = 0.02), the levels of released eosinophilic cationic protein were not significantly higher at LPR sites (P = 0.09). The levels of interleukin-8 (IL-8), but not IL-6, were greater at LPR than at DH sites. During the first 5 h of challenge there was greater mast cell activation and subsequent exudation of activated neutrophils at sites of developing LPR than at DH sites, possibly related to greater local IL-8 levels. The frequency of activated eosinophils was also greater at LPR sites. These different initial inflammatory responses could play a role in determining expression of LPR or DH reactions.

Immunopharmacology of human mast cells and basophils

Human mast cells and basophils play a key role in the pathogenesis of several immunological and inflammatory disorders, not only by producing inflammatory and fibrogenic mediators, but also by directly (CD40 ligand) and indirectly secreting various cytokines and chemokines. Studies carried out to evaluate the effects of drugs that modulate the release of mediators and cytokines from these cells have contributed to clarifying the biochemical mechanism by which immunological and non-immunological stimuli activate these cells. Significant differences have been documented between human mast cells and basophils as regard the pharmacological agents that modulate the release of mediators, between mast cells isolated from different anatomical sites, and between compounds of the same class of drugs. Efforts to gain insight into the biochemical events occurring during immunological activation of mast cells and basophils could lead to the identification of new biochemical targets for therapeutic interventions in several immunological disorders.

Mite antigen-induced IL-4 and IL-13 production by basophils derived from atopic asthma patients

BACKGROUND

There is increasing evidence for the role of basophils in the pathogenesis of atopic diseases such as bronchial asthma, atopic dermatitis and atopic rhinitis. Recently, it has been reported that basophils derived from healthy donors produce the immunoregulatory cytokines interleukin (IL)-4 and IL-13 after cross-linking of cell surface IgE. In addition to well-known inflammatory mediators, such as histamine and leukotriene C4. these cytokines produced by basophils are also considered to be associated with atopic diseases.

OBJECTIVE

Our first objective was to determine whether or not mite-sensitive atopic asthmatic basophils produce IL-4 and IL-13 in response to mite antigens. Our second objective was to investigate the relationship between antigen-specific or nonspecific IgE in the serum and the production of these cytokines in order to determine the association of basophil-derived cytokines with the pathogenesis of atopic asthma. Our final objective was to study how production of these cytokines could be regulated by some anti-asthma drugs.

METHODS

Basophils were purified from peripheral venous blood of 67 atopic asthma patients with elevated RAST for the house dust mite. Cells were stimulated with mite antigens for 6 hours and then IL-4 and IL-13 levels in the supernatants were measured by enzyme-linked immunosorbent assay (ELISA).

RESULTS

Mite-sensitive asthmatic basophils produced IL-4 and IL-13 when stimulated with mite antigens. Mite-induced IL-4 production peaked at 6 hours after the stimulation. whereas IL-13 production continued up to 24 hours. The higher the concentration of mite-specific IgE but not total IgE released in the serum, the more IL-4 and IL-13 were produced by basophils in response to mite antigens. The production of these cytokines was significantly suppressed by the anti-asthma drugs theophylline (IL-4, p<0.001, n=6; IL-13, p<0.001, n=10) and dexamethasone (IL-4, p<0.001, n=15; IL-13, p<0.001, n=10).

CONCLUSION

Mite-antigen-induced IL-4 and IL-13 production by basophils derived from mite-sensitive asthma patients was associated with the concentration of mite-specific IgE and may play an important role in the pathogenesis of atopic asthma. The inhibitory effect of dexamethasone and theophylline on allergic inflammation may be due to the inhibition of IL-4 and IL-13 production not only by T cells but also by basophils.

Factors determining spontaneous histamine release from human basophils purified with Percoll gradients and Dynabeads

Identification of factors influencing histamine release from purified and cultured basophil leukocytes is important for proper interpretation of results obtained on histamine release. This paper describes factors that influence spontaneous histamine secretion from human basophil leukocytes purified on Percoll gradients, followed by negative selection with Dynabeads. Anti-IgE and recombinant human interleukin-3 were used as model stimulants, and the purified basophil leukocytes were stimulated for 10 min and 6 h. The effect of the following conditions was examined: Percoll temperature, cell-suspension density, and serum in the media. The results showed that low Percoll temperature, high cell-suspension density, and the presence of serum in the media decreased spontaneous histamine release and increased maximal net histamine release upon stimulation.