Regulation of IgE synthesis in humans: a tale of two signals

Detection of Lectin Protein Allergen of Kidney Beans (Phaseolus vulgaris L.) and Desensitization Food Processing Technology

With the increase of food allergy events related to not properly cooked kidney beans (Phaseolus vulgaris L.), more and more researchers are paying attention to the sensitization potential of lectin, one of the major storage and defensive proteins with the specific carbohydrate-binding activity. The immunoglobulin E (IgE), non-IgE, and mixed allergic reactions induced by the lectins were inducted in the current paper, and the detection methods of kidney bean lectin, including the purification strategies, hemagglutination activity, specific polysaccharide or glycoprotein interactions, antibody combinations, mass spectrometry methods, and allergomics strategies, were summarized, while various food processing aspects, such as the physical thermal processing, physical non-thermal processing, chemical modifications, and biological treatments, were reviewed in the potential of sensitization reduction. It might be the first comprehensive review on lectin allergen detection from kidney bean and the desensitization strategy in food processing and will provide a basis for food safety control.

The Multifaceted B Cell Response in Allergen Immunotherapy

While allergen immunotherapy (AIT) for IgE-mediated diseases holds curative potential, the considerable heterogeneity in clinical outcomes may relate to the complex mechanisms of tolerance. The regulation of humoral immunity by AIT contributes to the suppression of allergic responses. Recent findings have revealed novel roles for IgA and IgG antibodies in the induction of tolerance. These mechanisms synergize with their ability to block allergen-IgE binding and mediate inhibitory signaling of effector cells of the allergic response. In addition, the regulatory activity of B cells in AIT extends beyond IL-10 secretion and induction of IgG₄. Here, we review the evolution of the B cell response during AIT with special emphasis on the novel protective mechanisms entailing humoral immunity.

Differential requirements for IL-4/STAT6 signalling in CD4 T-cell fate determination and Th2-immune effector responses

Improved analytical tools have revealed that the development and expression of a Th2 immune response can be broken down into distinct stages with respect to the cytokine microenvironment that is required. Although IL-4 and its STAT6-signalling pathway are critical for the expression of Th2 effector immune responses in peripheral tissues such as the skin, lung and gut, IL-4 and STAT6 signalling are not required for the initial generation of IL-4-producing Th2 cells in the lymph node. This finding reveals that we have yet to identify the key cytokine or microenvironment that stimulates the development of this most intriguing CD4(+) T-helper subset and emphasises the tissue specificity and timing of IL-4/STAT6-dependent Th2 effector responses.

Immunology

The concept of forbidden foods that should not be eaten goes back to the Garden of Eden and apart from its religious meanings it may also have foreshadowed the concept of foods that can provoke adverse reactions. Thus we could say that allergic diseases have plagued mankind since the beginning of life on earth. The prophet Job was affected by a condition that following the rare symptoms described by the Holy Bible might be identified as a severe form of atopic dermatitis (AD). The earliest record of an apparently allergic reaction is 2621 B.C., when death from stinging insects was first described by hieroglyphics carved into the walls of the tomb of Pharaoh Menes depicting his death following the sting of a wasp. In 79 A.D., the death of the Roman admiral Pliny the Elder was ascribed to the SO₂-rich gases emanating from the eruption of Mount Vesuvius. Hippocrates (460–377 B.C.) was probably the first to describe how cow’s milk (CM) could cause gastric upset and hives, proposing dietetic measures including both treatment and prevention for CM allergy.

Eosinophilic neuritis and eosinophilic panniculitis in a patient with advanced acquired immunodeficiency syndrome

The pruritic, papular eruption of human immunodeficiency virus with associated peripheral eosinophilia is well documented. We describe a 32-year-old African American man with advanced acquired immunodeficiency syndrome; a generalized painful, pruritic, papular rash; peripheral blood eosinophilia; and perineural eosinophilic infiltrates with eosinophilic panniculitis. To our knowledge, the latter 2 features have not been previously described in the literature on human immunodeficiency virus dermatoses. We propose that eosinophilic neuritis and eosinophilic panniculitis may represent additional findings in the spectrum of cutaneous disease seen in patients with advanced acquired immunodeficiency syndrome.

Los granulocitos eosinófilos: de residentes habituales de la mucosa gastrointestinal normal a protagonistas agresivos de la gastroenteritis eosinofílica

Because of their biological affinity for normal gastrointestinal (GI) mucosa, eosinophilic granulocytes are "normal residents" in the mucosa. This physiological GI eosinophilia translates into a state of "permanent normal inflammation", which means that the mucosa's local immune system is constantly confronted by dietary proteins and indigenous microorganisms. This eosinophilic infiltration of the GI mucosa is increased, reactively, in the course of local inflammatory processes, collagenosis, infections (especially helminthic infections), vasculitis, neoplasms and IgE-dependent allergic reactions to food. Lastly, GI eosinophilia that is clearly aggressive, both because of its intensity and its persistence, is what characterizes eosinophilic gastroenteritis. In the present article, we summarize the ethiopathogenic and clinico-epidemiological features of this process, as well as its position within the field of immunopathologic food intolerance.

Las esofagogastroenteritis eosinofílicas dentro del espectro de las alergias alimentarias

Under normal conditions, the digestive tube immune system is capable of establishing an effective plan of tolerance to food that is eaten daily by the human beings. However, this tolerance plan sometimes fails and in the final steps of this immunological dysreaction, other cellular elements, usual residents of the digestive mucous, such as eosinophil granulocytes, generally participate, together with the main cells of this system. This is the case, among others, of the so-called EGE-Eos. The authors summarize the spectrum of pathogenic options of these immunological food intolerances that range from those in which "all" depend on a specific IgE (GI food anaphylaxis) and those others in which "nothing" depends on this reagin (celiac sprue). An intermediate position would be occupied by the EGE-Eos in which there seems to be overlapping of immune reactions of cellular character together with a certain role of the IgE. These pathogenic pathways frequently cross a tangle of cellular and molecular events that cannot be untangled with either an image or one thousand words.

Is occupational asthma to diisocyanates a non-IgE-mediated disease?

BACKGROUND

Exposure to diisocyanates in the workplace is an important cause of occupational asthma. The majority of patients with diisocyanate-induced asthma have no detectable diisocyanate-specific IgE antibodies in serum. There has been much debate as to whether this is due to diisocyanate-induced asthma being mediated by non-IgE mechanisms or whether it is the result of using inappropriate conjugates.

OBJECTIVE

We sought to determine whether RNA message for Cepsilon, IL-4, and other associated inflammatory markers could be detected locally within the bronchial mucosa after diisocyanate challenge.

METHODS

Fiberoptic bronchoscopic bronchial biopsy specimens were obtained at 24 hours after both a control and an active challenge in 5 patients with positive and 7 patients with negative inhalation test responses to diisocyanates. Using both immunohistochemistry and in situ hybridization, we determined mRNA for Cepsilon, IL-4, IL-5, and other associated inflammatory markers.

RESULTS

There was a striking absence of Cepsilon and IL-4 mRNA-positive cells in bronchial biopsy specimens from patients challenged with diisocyanate (Cepsilon median of 0 and interquartile range of 0-1.85; IL-4 median of 0 and interquartile range of 0-0.85). In contrast, there were increased numbers of IL-5-, CD25-, and CD4-positive cells and a trend toward an increase in eosinophils after active challenge with diisocyanate.

CONCLUSION

We found a striking absence of both bronchial Cepsilon and IL-4 RNA message after inhalation challenge with diisocyanates, irrespective of whether the challenge test response was positive or negative. We propose that diisocyanate-induced asthma is a non-IgE-mediated disease, at least in patients in whom specific IgE antibodies to diisocyanates are undetectable.

Lectins interact differentially with purified human eosinophils, cultured cord blood-derived mast cells and the myeloid leukaemic cell line AML14.3D10: induction of interleukin-4 secretion is conserved among granulocytes, but is not proportional to agglutination or lectin-glycoprotein interaction

BACKGROUND

Atopy is closely associated with the cellular T helper type-2 (Th2) phenotype, that is dominated by the pleiotrophic cytokine IL-4. The cellular source of IL-4 has yet to be determined, although basophils have been proposed. Eosinophils and mast cells are likely contenders investigated here, and the eosinophil-like leukaemia line AML14.3D10 is compared to eosinophils as an in vitro culturable model for eosinophils. Lectins can cross-link-specific surface glycoproteins and are found in the ingested (processed foods) and inhaled (airborne pollen grains) human environment. Therefore it is of interest to determine whether lectins can elicit the release of IL-4 from Th2-associated granulocytes other than basophils.

METHOD

This study investigated the ability of eosinophils, AML14.3D10 and mast cells to secrete preformed IL-4 in response to stimulation with lectins, and explored molecular mechanisms underlying the interaction.

RESULTS

Purified eosinophils and basophils, and cultured mast cells and AML14.3D10 cells were incubated with 1 micro m lectin. Agglutination was scored by microscopy. IL-4 secretion was measured by enzyme-linked immunosorbent assay. Biotinylated lectins were used to determine binding to cells by flow cytometry and in lectin blots of sodium dodecyl sulphate (SDS) gels.

DISCUSSION

Purified human eosinophils, AML14.3D10 cells and cultured mast cells secrete IL-4 with a pattern similar to that found in basophils when stimulated with a panel of reactive and unreactive lectins. The lectin SNA induces IL-4 secretion from mast cells and basophils, but not from eosinophils or AML14.3D10. Eosinophils appear to secrete only pre-formed IL-4, whereas mast cells may synthesize IL-4 on ligation with the lectin LCA. Lectins that agglutinate the granulocytes investigated do not necessarily induce secretion of IL-4. Lectins that elicit secretion of IL-4 bind more to eosinophils than unreactive lectins as determined by flow cytometry and lectin blotting of SDS gels.

CONCLUSION

As granulocytes with functions related to that of basophils, eosinophils, AML14.3D10 and cultured mast cells respond to stimulation with lectins similarly to basophils. This emphasizes the possibility that eosinophils and mast cells may be linked in their cellular heritage as the cellular partners, and lectins as ligands, may contribute to the maintenance of a Th2-favoured microenvironment that is thought to underlie the allergic march.

Basophil recruitment and IL-4 production during human allergen-induced late asthma

BACKGROUND

Basophils represent an important source of inflammatory mediators and cytokines after IgE-dependent activation in human beings.

OBJECTIVE

To assess the role of basophils in allergic asthma, we measured the number of basophils in the bronchial mucosa and their capacity to express IL-4 mRNA and protein during allergen-induced late asthmatic responses.

METHODS

Fiberoptic bronchoscopic bronchial biopsies were obtained at 24 hours from sites of segmental bronchial allergen challenge and control sites in 19 patients with atopic asthma and 6 nonatopic healthy volunteers. Basophil numbers were assessed by immunohistochemistry through use of mAb 2D7. IL-4 mRNA--positive cells were detected through use of in situ hybridization and colocalized to basophils through use of sequential immunohistochemistry/in situ hybridization. IL-4 protein was detected and colocalized to basophils through use of dual immunohistochemistry.

RESULTS

After allergen challenge, there was an increase in the median number of 2D7-positive basophils per square millimeter in the bronchial mucosa in patients with asthma (0.9 cells/mm(2) at baseline to 8.8 cells/mm(2) after challenge; P =.002), which also was significantly higher than what was seen in nonasthmatic controls (P =.01). Similarly, IL-4 mRNA--positive cells were increased at 24 hours in patients with asthma (1.4 to 14) in comparison with controls (0 to 0; P =.02). Colocalization studies revealed that 15% and 41% of the basophil population in patients with asthma after allergen-challenge expressed, respectively, IL-4 mRNA and protein. Conversely, 19% of IL-4 mRNA-positive cells and 72% of IL-4 protein--positive cells were accounted for by basophils.

CONCLUSION

After allergen provocation in sensitive patients with atopic asthma, basophils are recruited to the bronchial mucosa and express IL-4 mRNA and protein, which might contribute to local IgE synthesis and/or tissue eosinophilia or other aspects of allergic inflammation during late responses and ongoing asthma.

Environmental factors favoring the allergen-specific Th2 response in allergic subjects

Allergen-reactive type 2 helper T cells (Th2) play a triggering role in the activation and/or recruitment of IgE antibody-producing B cells, mast cells, and eosinophils, i.e., the cellular triad involved in the allergic inflammation. Interleukin (IL)-4 production at the time of antigen presentation to the Th cell is critical for the development of Th2 cells. Other cytokines, such as IL-1 and IL-10, and hormones, such as calcitriol and progesterone, also play a positive role. In contrast, cytokines such as interferon (IFN)-alpha, IFN-gamma, IL-12, and transforming growth factor (TGF)-beta, and relaxin play a negative regulatory role on the development of Th2 cells. However, the mechanisms underlying the preferential activation by environmental allergens of Th2 cells in atopic individuals still remain obscure. Some gene products selectively expressed in Th2 cells or selectively controlling the expression of IL-4 have recently been described. Moreover, cytokines and other gene products that dampen the production of IL-4, as well as the development and/or the function of Th2 cells, have been identified. These findings allow us to suggest that the upregulation of genes controlling IL-4 expression and/or abnormalities of regulatory mechanisms of Th2 development and/or function may be responsible for Th2 responses against common environmental allergens in atopic subjects.

B-cell isotype control in atopy and asthma assessed with cDNA array technology

B-cell isotype switching and the production of IgE is regulated by a variety of gene products through different mechanisms. A better understanding of these processes has the potential to identify markers of disease and new therapeutic targets. The aim of the study was to investigate human B-cell isotype control and IgE production in atopy and asthma with cDNA array technology. Eighteen atopic asthmatic, eight atopic nonasthmatic, and fourteen healthy control subjects were included. Peripheral blood mononuclear cells were separated by gradient centrifugation, mRNA was purified, and the reverse-transcribed probes were hybridized to cDNA membranes. Group differences were assessed with the Mann-Whitney U-test. Twenty-three of seventy-eight tested IgE-related genes had significantly altered expression in atopy and asthma compared with that in the healthy subjects. The differentially expressed genes include surface molecules involved in T- and B-cell interaction and activation, cytokines, intracellular signaling products, and transcription factors. In conclusion, both atopic nonasthmatic and atopic asthmatic individuals had activated proinflammatory pathways, a minimal requirement for B-cell isotype switching, and a clear net pro-IgE cytokine climate.

Expression of CD23/CD21 and CD40/CD40 ligand in vernal keratoconjunctivitis

PURPOSE

The overproduction of immunoglobulin E (IgE) antibodies is associated with vernal keratoconjunctivitis (VKC). CD23/CD21 and CD40/CD40 ligand (CD40L) interactions have been proposed to be involved in the regulation of IgE synthesis. The purpose of the present study was to investigate the presence and distribution of CD23, CD21, CD40 and CD40L in the conjunctiva from patients with active VKC.

METHODS

Conjunctival biopsy specimens from 8 subjects with active VKC and 6 control subjects were studied. We used immunohistochemical techniques and a panel of monoclonal antibodies (mAbs) directed against CD23, CD21, CD40 and CD40L. In addition, a panel of mAbs were used to characterise the composition of the inflammatory infiltrate.

RESULTS

In the normal conjunctiva, basal epithelial cells and vascular endothelial cells in the upper substantia propria showed a constitutive very weak immunoreactivity for CD40. The immunoreactivity for CD23, CD21 and CD40L was absent. In VKC specimens, the stromal inflammatory infiltrate was orgnanised as a diffuse infiltrate and as small lymphoid follicles consisting of CD20+ B lymphocytes intermingled with smaller numbers of CD3+ T lymphocytes, and CD68+ monocytes/macrophages. Lymphocytes in the centre of the lymphoid follicles showed CD23 and CD21 immunoreactivity. CD40 immunoreactivity in epithelial cells and vascular endothelial cells was stronger in VKC specimens than in control eyes. Furthermore, the majority of mononuclear cells, including T and B lymphocytes, showed immunoreactivity for CD40. CD40L immunoreactivity was not detected.

CONCLUSION

B lymphocytes in the lymphoid follicles expressing CD23, CD21 and CD40 are activated and might be precursors of IgE-producing B cells. These results suggest that the conjunctiva might contribute to IgE synthesis.

Testing for gene-gene interaction controlling total IgE in families from Barbados: evidence of sensitivity regarding linkage heterogeneity among families

Genetic heterogeneity has been proposed as a hallmark feature of allergic disease. To test the hypothesis that total IgE levels are jointly influenced by a locus on chromosome 12q21.1-q21.31 and a locus on 17q11.2-q21.2, we conducted multipoint allele-sharing analyses using nonparametric linkage (NPL) methods on Afro-Caribbean families from Barbados to test for evidence of gene-gene interactions. Significant correlations were observed between NPL scores at D12S1052 and both D17S1293 and D17S1299 for a dichotomized phenotype of total IgE. An analysis of family-specific NPL scores revealed that evidence for interaction was being driven largely by one multiplex pedigree (NPL = 12.01, 12.23, and 12.16 at D12S1052, D17S1293, and D17S1299, respectively). Using the programs SIMWALK (v2.0) and GOLD, a different set of haplotypes in this influential family was observed around D12S1052 and the 17q loci compared to the other Barbados pedigrees. Our findings are a classic example of founder effect, provide evidence for sensitivity of this type of linkage analysis to unusual pedigrees, and highlight an element of genetic heterogeneity that has been given little attention in the study of complex traits.

Hydrocortisone enhances allergen-specific IgE production by peripheral blood mononuclear cells from atopic patients with high serum allergen-specific IgE levels

BACKGROUND

Although there is convincing evidence that human B cells can be induced to produce IgE by a combination of interleukin 4 (IL-4) and hydrocortisone (HC) in atopic subjects, it is still uncertain if this performs the same functions in allergen-specific IgE synthesis.

OBJECTIVE

This study was designed to investigate the differences of IgE regulation between atopics and nonatopics, interactions of HC with IL-4, and the correlation between in vitro total IgE, allergen-specific IgE synthesis and serum IgE levels.

METHODS

Peripheral blood mononuclear cells (PBMCs) from 16 atopic asthma patients sensitive to Dermatophagoides farinae and seven nonatopic controls were cultured with IL-4 and/or HC. Total IgE and D. farinae-specific IgE in culture supernatant were measured by ELISA and FAST.

RESULTS

IL-4 increased total IgE synthesis in PBMCs from both atopics and nonatopics, whereas, HC had this effect only in some atopics who showed spontaneous IgE production in vitro. HC acted synergistically with IL-4 in total IgE synthesis. Their effects were more remarkable in cases with lower total serum IgE levels. PBMCs from eight of 16 atopics produced D. farinae-specific IgE in vitro either spontaneously or by IL-4 and/or HC. HC had more profound effects than IL-4 in these patients. They also showed higher total IgE synthesis by HC, and higher specific serum IgE levels than the others. IL-4 and/or HC did not induce any D. farinae-specific IgE synthesis by PBMCs from nonatopics.

CONCLUSION

HC had a more profound effect than IL-4 on the induction of D. farinae-specific IgE synthesis in atopic patients with high serum allergen specific IgE levels. Further studies to determine the causes of these effects, such as the presence of long lived allergen specific B cells as the result of the priming effect of IL-4 in vivo, may be needed.

Hyperimmunoglobulin-E syndrome with recurrent infection: a review of current opinion and treatment

Hyperimmunoglobulin E (hyper-IgE) syndrome with recurrent infection is a rare idiopathic primary immunodeficiency. It consists of a severe dermatitis with recurrent abscess formation, respiratory tract infections and very high titres of serum immunoglobulin E (IgE). Hyper-IgE syndrome is also associated with skeletal abnormalities. Variability of presentation makes it easy to confuse the diagnosis with that of severe atopy or other rare immunodeficiencies. The aim of this article is to review the literature in order to consider the clinical findings, etiology and treatment of this syndrome.

The role of thymus-dependent T cells in hexachlorobenzene-induced inflammatory skin and lung lesions

The involvement of thymus-dependent T cells in the inflammatory skin and lung lesions and spleen effects induced by hexachlorobenzene (HCB) was investigated by using genetically athymic and euthymic WAG/Rij rats and Brown Norway (BN) rats with or without depletion of T cells by adult thymectomy, lethal irradiation, and bone marrow reconstitution. Rats were exposed to diets with no supplementation or diets supplemented with 150 or 450 mg HCB per kg diet for 4 (BN) or 6 (WAG/Rij) weeks. Skin lesion development and body weight gains were assessed during exposure and spleen and liver weights as well as histopathologic changes in skin, lung, and spleen were assessed after exposure. Oral HCB exposure of athymic and euthymic rats of both rat strains resulted in a dose-dependent increase of relative liver weight at doses of 150 and 450 mg/kg HCB and increased relative spleen weights at a dose of 450 mg/kg. HCB exposure of both strains further resulted in inflammatory changes in skin, lungs, and splenic red pulp independent of the T cell status except for skin lesions in the BN strain. HCB-exposed T cell-competent BN rats showed faster skin lesion development than the T cell-depleted rats, although qualitatively and quantitatively similar skin pathology was observed at the end of the 4-week exposure in both groups. In the WAG/Rij strain skin lesions could not be comparatively assessed due to preexistent inflammatory skin pathology in the nude rats. This study showed that thymus-derived T cells are not required for the induction of skin and lung pathology and splenic changes by HCB and therefore it is suggested that HCB acts differently from many allergenic and autoimmunogenic low molecular weight compounds that trigger pathology via thymus-dependent mechanisms. A role for mononuclear phagocytes and, in BN rats, eosinophilic granulocytes, in the HCB-induced pathology is suggested since these cells were prominently present in the HCB-induced lesions.

Serum cytokines and increased total serum IgE in alcoholics

BACKGROUND

It has been reported that total serum IgE is increased in alcohol abusers, but the mechanisms responsible are not known. Production of IgE depends on B-cell stimulation by both antigens and some cytokines, particularly IL-4 and IL-13. Chronic alcoholism and alcoholic liver disease are accompanied by changes in cytokine production.

AIM OF THE STUDY

To evaluate if IgE increase in alcoholics could be associated to a ethanol-induced imbalance of the cytokine profile.

PATIENTS AND METHODS

A total of 65 patients (53 males and 12 females, aged 47 +/- 12 years), admitted to the hospital because of ethanol abstinence symptoms entered the study. On admission, total serum IgE was measured by chemiluminescent EIA and serum IL-4, IL-5, IL-6, IL-8, IL-10, IL-12, IL-13, and interferon-gamma were measured by ELISA. Data were compared with those of 40 healthy control subjects.

RESULTS

Serum IgE, IL-6, IL-8, IL-10, IL-12, and IL-13 were found to be high in alcoholic patients compared with healthy volunteers. Some parallelism was observed between serum IgE and both serum IL-10 and IL-13 were increased in alcoholics.

CONCLUSIONS

Total serum IgE elevation in alcoholics with abstinence syndrome is accompanied by an increase of some type 2 cytokines. Ethanol-induced alterations in the cytokine profile may contribute to increased IgE levels in alcoholics.

Immediate hypersensitivity in adults with IgG deficiency and recurrent respiratory infections

BACKGROUND

Little is known about the prevalence of atopy in adults with recurrent respiratory infections and IgG deficiency.

OBJECTIVE AND METHODS

To elucidate this aspect, we skin-tested 95 consecutive adults with respiratory infections, subnormal levels of IgG subclasses or common variable immunodeficiency and usually poor response to vaccination. In 50 subjects we also measured total IgE.

RESULTS

We found 67 subjects with IgG subclass deficiency, 21 subjects with mild (partial) and 5 with usual common variable immunodeficiency, and 2 subjects with functional IgG deficiency. Atopy was encountered in 42/95 subjects, 33/44 (75%) with asthma, 7/19 (38%) with isolated rhinosinusitis, 1/27 (4%) with chronic obstructive lung disease, and 1/5 (20%) with both the latter disease and asthma, respectively. Atopy was preferentially clustered in subjects with asthma (P < .05) who were less than 40 years of age (P < .05) and nonsmoking. Atopy was not affected by the type of IgG deficiency, unless it was usual common variable immunodeficiency, in which case the skin tests tended to be negative (4/5). Total IgE was within normal range but less elevated than usually seen in asthma or chronic obstructive lung disease. Total IgE was independent of the type of IgG deficiency, except for usual common variable immunodeficiency in which it remained < 10 IU/mL.

CONCLUSIONS

In adults with symptomatic IgG deficiency, the prevalence of immediate hypersensitivity and its modulation by age and smoking are similar to the referred, non-IgG deficient population; however, total IgE may be lower in the former than in the latter. In common variable immunodeficiency, consistent with the literature data, both the prevalence of atopy and serum total IgE are decreased.

Food allergy. Part 1: immunopathogenesis and clinical disorders

Up to 8% of children less than 3 years of age and approximately 2% of the adult population experience food-induced allergic disorders. A limited number of foods are responsible for the vast majority of food-induced allergic reactions: milk, egg, peanuts, fish, and tree nuts in children and peanuts, tree nuts, fish, and shellfish in adults. Food-induced allergic reactions are responsible for a variety of symptoms involving the skin, gastrointestinal tract, and respiratory tract and may be caused by IgE-mediated and non-IgE-mediated mechanisms. In part 1 of this series, immunopathogenic mechanisms and clinical disorders of food allergy are described.

Regulation of immunoglobulin production in hyper-IgE (Job's) syndrome

BACKGROUND

The hyper-IgE (HIE), or Job's, syndrome is a rare, complex disorder characterized by high levels of serum IgE in childhood and chronic dermatitis with recurrent, often severe sinopulmonary and skin infections. Although the etiology of HIE syndrome is unknown, there is evidence that patients with HIE have abnormalities in cellular immune responses, as well as in the production of polyclonal and antigen-specific antibodies. Furthermore, there appears to be a common (but still undefined) mechanism underlying the regulation of IgE and IgG4 in this condition.

OBJECTIVE

We sought to assess the role of cytokines or cytokine receptor blockade in regulating IgE and IgG4 production in HIE.

METHODS

PBMCs were isolated from patients with HIE (n = 9) and normal individuals (n = 8), and IgE and IgG4 production was assessed spontaneously, in the presence of recombinant IL-4, IL-13, IL-6, IL-8, IL-12, and IFN-gamma, under conditions in which the IL-4R was blocked or when these cytokines were neutralized by specific monoclonal or polyclonal antibodies.

RESULTS

In PBMCs from patients with HIE, a significant (P <.01) reduction in the spontaneously produced IgE (and IgG4) was induced by either IFN-gamma or IL-12, although neither cytokine could totally abrogate the immunoglobulin production. Whereas spontaneous IgE (and IgG4) production was not affected by exogenous IL-4 and IL-13, neutralizing antibodies to IL-4 and IL-13 also significantly (P <.01) reduced the production of IgE and IgG4, a finding supported by the observation of increased expression of IgE germline transcripts in these patients. In contrast to the neutralization of IL-4 and IL-13 protein, anti-IL-4R antibodies or soluble IL-4R completely suppressed IgE and IgG4 production in HIE. Similarly, IL-8 or antibodies to IL-6 and TNF-alpha, cytokines known to affect IL-4-dependent IgE production, completely inhibited both IgE and IgG4 production.

CONCLUSION

These data show that overproduction of IgE and IgG4 can be regulated by a number of cytokines affecting the IL-4-dependent pathway of IgE/IgG4 production in HIE and suggest new targets for therapeutic intervention.

Increased type 2 cytokine expression by both CD4+ CD45RO+ T cells and CD8+ CD45RO+ T cells in blood circulation is associated with high serum IgE but not with atopic dermatitis

Type 2 cytokines, such as interleukin-4 (IL-4) and IL-13, are associated with immunoglobulin E (IgE) production. This association has also been observed in CD8+ T cells from patients infected with leprosy and human immunodeficiency virus (HIV). Using intracellular cytokine staining and flow cytometry, the cytokine profile [IL-2, IL-4, IL-10, IL-13, and interferon (IFN)-gamma] of both CD4+ and CD8+ memory/effector T cells circulating in atopic dermatitis (AD) patients was investigated at the single cell level. The levels of type 2 cytokines in CD4+ T cells or CD8+ T cells in AD patients with high levels of serum IgE (AD-H), low levels of serum IgE (AD-L), and healthy controls were compared. Increased production of IL-4 and IL-13 in both CD4+ CD45RO+ T cells and CD8+ CD45RO+ T cells after 4 h in vitro stimulation with phorbol 12-myristate 13-acetate and ionomycin, was more prominent in AD-H patients than in AD-L patients or healthy controls, whereas IFN-gamma-producing CD4+ CD45RO+ T cells and CD8+ CD45RO+ T cells were relatively diminished in AD-H patients. CD4+ T cells and CD8 + T cells from AD-H patients, cultured for 48 h with phorbol 12-myristate 13-acetate and ionomycin, released larger amounts of IL-4 and IL-13 but smaller amounts of IFN-gamma than both types of cells from AD-L patients or healthy controls. In addition, when stimulated with immobilized anti-CD3 monoclonal antibody (MoAb) and anti-CD28 MoAb, CD4+ CD45RO+ T cells and CD8+ CD45RO+ T cells from AD-H patients contained more IL-4-producing cells but fewer IFN-gamma-producing cells compared with healthy controls. Finally, spontaneous mRNA expression of IL-4 in blood CD8+ CD45RO+ T cells isolated from AD-H patients was increased, as determined by reverse transcriptase-polymerase chain reaction. Therefore, in AD patients with high IgE levels, type 2 cytokine (IL-4 and IL-13) expression is associated with IgE production, in both CD4+ CD45RO+ T cell and CD8+ CD45RO+ T cell subsets.

Long-term therapy with recombinant interferon-gamma (rIFN-gamma) for atopic dermatitis

BACKGROUND

Interferon-gamma (IFN-gamma) is a potent cytokine that modulates IL-4-induced immune responses. Atopic dermatitis is associated with increased IgE levels and decreased IFN-gamma production. Recent phase I and phase II studies have suggested that short-term rIFN-gamma therapy is effective in the treatment of severe atopic dermatitis.

OBJECTIVE

We evaluated the safety and efficacy of long-term use of rIFN-gamma for severe atopic dermatitis.

METHODS

Fifteen patients were treated for a minimum of 22 months with 50 micrograms/m2 rIFN-gamma qd or qod. Patients were monitored every 3 months for safety, efficacy, and linear growth in pediatric patients.

RESULTS

Data represented a total of 47 patient years, which included 29 pediatric patient years. There was a statistically significant decrease in mean total body surface area involvement over time (P < .001, ANOVA). Mean total body surface area involvement was 61.6% at baseline and decreased to 18.5% at 24 months (P < .001). Likewise, there was a statistically significant decrease in the clinical severity parameters. The mean total clinical severity score was 11.4 at baseline and decreased to 6.3 at 24 months (P < .001). Statistically significant decreases in WBC, neutrophil counts, and eosinophil counts were observed compared with baseline counts. No other significant laboratory abnormalities or growth problems were seen.

CONCLUSIONS

We conclude that rIFN-gamma appears to be a safe long-term therapy for patients with severe atopic dermatitis.

Human lung mast cells release small amounts of interleukin-4 and tumour necrosis factor-alpha in response to stimulation by anti-IgE and stem cell factor

Recent reports have suggested that mast cells are capable of producing and releasing a number of pro-inflammatory cytokines. However, these studies have mainly been carried out using murine tissue culture derived mast cells and it is known that these cells differ markedly in their functional properties from isolated human mast cells. It was therefore essential to study the release of cytokines from the latter cell type. On immunological stimulation with anti-immunoglobulin E (anti-IgE) or stem cell factor (SCF), purified human lung mast cells released, within 2-10 min, small amounts of tumour necrosis factor-alpha (10.5 +/- 2.9 pg/10(6) mast cells and 17.9 +/- 7.9 pg/10(6) mast cells, respectively) and interleukin-4 (5.3 +/- 2.5 pg/10(6) mast cells and 8.0 +/- 3.2 pg/10(6) mast cells, respectively). After longer periods of activation (30 min-4 h). the amounts of cytokines released from stimulated cells decreased to levels which were below those of the unstimulated cells. This possible degradation of cytokines by mast cells could not be prevented by the addition of protease inhibitors.

Clinical significance of eosinophilia in HIV-infected individuals

PURPOSE

To assess the clinical significance of peripheral eosinophilia in HIV-infected individuals.

METHODS

In a retrospective case-control study we compared 42 HIV-infected patients (cases) with peripheral eosinophilia (absolute eosinophil count > 500 cells/mm3) with 84 HIV-infected controls without eosinophilia. Cases were matched to controls by date, and by CD4 cell count. Data on clinical parameters possibly associated with eosinophilia were collected and compared among cases and controls.

RESULTS

Eosinophilia was seen in patients with late-stage HIV disease (median CD4 cell count of 26 cells/mm3). Cases were more likely to be black (52% versus 18%, P = 0.0001), have pruritus (50% versus 20%, P = 0.002), and have a physician-documented rash (76% versus 52%, P = 0.02). Specific cutaneous diagnoses that were more prevalent in cases versus controls were eosinophilic folliculitis (24% versus 1% P = 0.0001), atopic dermatitis (14% versus 1%, P = 0.01), and prurigo nodularis (7% versus O, P = 0.07). Other parameters commonly associated with eosinophilia such as allergic reactions, parasitic infection, malignancy, and adrenal insufficiency were not found at higher incidence in cases.

CONCLUSIONS

Eosinophilia in AIDS patients is associated with cutaneous disease, but not with other conditions commonly associated with eosinophilia including parasitic infections, allergic reactions, or malignancy. Extensive work up for asymptomatic eosinophilia in patients with AIDS and cutaneous disease is not warranted.

Does puberty interfere with asthma?

This study reviews whether, to date, scientific evidence exists that puberty interferes with the occurrence of asthma. This question was triggered by three points: (a) clinical experience with asthma as a relatively benign disease that children often 'grow out of'; (b) observations implying that asthma can change during fluctuations of sexual steroid hormones; and (c) knowledge that puberty is an age of deep hormonal changes. No scientific evidence was found that pubertal changes interfere with the occurrence of asthma. Nevertheless, there is a general agreement about the influence of age and sex on its outcome. The overall occurrence of the disease, which is highest in childhood, declines with age. In the wane phenomena, puberty does not seem to be more important than previous ages. Furthermore, the pattern of occurrence is different in the two sexes. Boys have more asthma before 10 years of age or the mid-teens. Girls then overtake boys and have more asthma up to the years of sexual maturity. During the fifth or sixth decade, asthma again seems to become slightly more prevalent in men than women, or at least the difference between the sexes disappears. It is concluded that the risk of asthma is not influenced by puberty. Age and sex seem to be more important factors, although the reason for this is unknown.

Direct and sequential switching from mu to epsilon in patients with Schistosoma mansoni infection and atopic dermatitis

Immunoglobulin isotype switching to IgE in patients infected with Schistosoma mansoni and patients with atopic dermatitis was studied. Patients with parasitic infections or allergic diseases have a higher production of IgE. We found a four-fold increased production of I epsilon RNA in both patient groups as compared to control donors. The increased expression of germ-line transcripts correlates with higher serum IgE levels. Nested primer polymerase chain reaction was used to generate S mu/S epsilon fragments from DNA of patient peripheral blood mononuclear cells. Twenty-nine out of fourty sequenced switch fragments had undergone direct joining from S mu to S epsilon whereas seven fragments showed mono sequential switching from S mu via either S mu, S gamma2, S gamma4 or S epsilon to S epsilon and four fragments demonstrated double sequential switch: S mu/S mu/S gamma1/S epsilon, S mu/S gamma2/S epsilon/S epsilon or S mu/S gamma1/ S gamma2/S epsilon. The sequential switching had occurred either via deletions or inversions. Mapping of the breakpoints showed hot spots for recombination within S mu, S gamma1 and S epsilon. To our knowledge, this is the first in vivo study in humans demonstrating that switching to IgE can occur from sequential rearrangements via gamma1, gamma2 or gamma4.

Anti-interleukin-4 inhibits immunoglobulin E production in a murine model of atopic asthma

Immunoglobulin E (IgE) plays an important role in allergy, acting as an initiating factor and being involved in its persistence and exacerbations. As interleukin-4 (IL-4) is critical in IgE synthesis, we propose that treatment of mice with monoclonal anti-IL-4 (11B11) prior to active sensitization with ovalbumin will inhibit IgE synthesis, therefore arresting the allergic process at an early stage. Mice treated with 11B11 and sensitized with saline or ovalbumin had significantly less serum IgE than their respective control groups which were treated with saline (p < 0.05). This study suggests that anti-IL-4 may be a prophylactic agent in asthma and allergic disease.

Purified human peripheral blood basophils release interleukin-13 and preformed interleukin-4 following immunological activation

Recent studies have shown that human basophils, like mast cells, generate interleukin (IL)-4 following immunological activation and may thus participate in late-phase allergic and inflammatory processes. Here, we report the capacity of human basophils to release IL-13 within 24 h following stimulation with anti-IgE. Additionally, in 14 out of 31 experiments, we observed that basophils rapidly release performed IL-4 within 5-10 min, as well as newly generated IL-4, which was released 4 h following stimulation of the cells with anti-IgE. In contrast to the biphasic release of IL-4 from the cells, no preformed IL-13 was detected at earlier times (5-30 min). Preformed IL-4 and IL-4 and IL-13 generated de novo were also released after stimulation of the cells with IL-3; an enhanced production of these cytokines was observed using a combination of IL-3 and anti-IgE. We conclude from these data that, by releasing performed IL-4 and IL-4 and IL-13 generated de novo, human basophils may be centrally involved in the orchestration of allergic inflammation by providing a trigger to IL-4-mediated T helper 2 lymphocyte activation, B cell IgE switching, and increased vascular adhesion molecule expression.

Studies on the immunoglobulin-E system of the common marmoset in comparison with human data

In the common marmoset (Callithrix jacchus jacchus) immunoglobulin E (IgE) serum levels and IgE synthesis of peripheral blood mononuclear cells (PBMC) in vitro were investigated in order to look for homologies to the human system. While IgE was not found in marmoset blood plasma with three commercial antihuman IgE-kits with monoclonal antibodies (mAbs), two other kits using polyclonal antibodies against human IgE revealed detectable IgE concentrations of up to 10 kU/liter in plasma samples of 19 out of 21 marmosets. In accord with human data, rhIL-4 showed biological functions under in vitro conditions in PBMC of the New World monkey. Proliferation, measured by 3H-thymidine incorporation, of isolated PBMC of marmosets could be induced by rhIL-4. FACScan analysis showed an enhanced expression of the low affinity IgE receptor CD23 (Fc epsilon RII) on CD20+ B lymphocytes after incubation with rhIL-4. Furthermore, PBMC from marmosets could be stimulated by IL-4 alone or in combination with dexamethasone as well as with lipopolysaccharide (E. coli) to produce IgE in culture. The results indicate that Callithrix jacchus is using an IgE system that is rather similar to that of humans, although not completely identical. Antihuman mAbs and rhIL-4 can be used to investigate IgE regulation in vitro of marmoset PBMC. These data encourage the development of a primate animal model for studying possible modifications of the IgE system under pathological conditions to find new therapeutic strategies in atopic diseases.

Specific IgE detected by ELISA and immunoblot after human cytomegalovirus infection (HCMV) in renal transplant (RT) recipients

BACKGROUND

Specific HCMV IgE response has been reported by some authors, and was proposed as a valuable virologic marker of CMV infection.

OBJECTIVES

we evaluated specific HCMV IgE in renal transplant patients with active (primary and secondary) HCMV infection with special interest to symptomatic infections.

STUDY DESIGN

Specific IgE was tested retrospectively by ELISA and immunoblot (IB) on sera of 55 RT patients who were followed before and after transplantation with virologic markers of CMV infection.

RESULTS

Total serum IgE levels were similar in control group and in patients with primary and secondary HCMV infections. Anti-CMV specific IgE response by ELISA was more frequently found in patients with primary infection (76.9%) than in patients with secondary infection (47.1%). These specific IgE reacted on immunoblot with a 150 kDa protein in 84.6% of patients with primary infection and 94.1% with secondary infections; and reacted with rp52 (pUL44) in 76.9% of primary infection and 47.1% of secondary infection.

CONCLUSIONS

Anti-CMV specific IgE tested by immunoblot and ELISA is a marker of CMV infection. It was clearly detected in cases of active infection (primary and secondary) and was present in cases with severe CMV clinical manifestations. In contrast, anti-CMV specific IgE, was consistently negative among healthy blood donors. This is the first report of CMV proteins detected by IgE immunoblot.

Development in vitro of human CD4+ thymocytes into functionally mature Th2 cells. Exogenous interleukin-12 is required for priming thymocytes to produce both Th1 cytokines and interleukin-10

Fresh postnatal thymocyte cell suspensions were directly cloned under limiting dilution conditions with either phytohemagglutinin or toxic shock syndrome toxin-1 (TSST-1), a bacterial superantigen. Cultures contained allogenic irradiated feeder cells and interleukin (IL)-2, in the absence or presence of exogenous IL-4, interferon (IFN)-gamma or IL-12. The resulting CD4+ T cell clones generated under these different experimental conditions were then analyzed for their ability to produce IL-2, IL-4, IL-5, IL-10, IFN-gamma and tumor necrosis factor (TNF)-beta in response to stimulation with phorbol 12-myristate 13-acetate (PMA) + anti-CD3 monoclonal antibody or PMA + ionomycin. Different from T cell clones generated from peripheral blood, virtually all CD4+ T cell clones generated from human thymocytes produced high concentrations of IL-2, IL-4 and IL-5, but no IFN-gamma, TNF-beta or IL-10. Moreover, after activation, these clones expressed on their surface membrane both CD30 and CD40 ligand, but not the product of lymphocyte activation gene (LAG)-3, and provided strong helper activity for IgE synthesis by allogeneic B cells. The Th2 cytokine pattern could not be modified by the addition of IFN-gamma. However, upon addition of exogenous IL-12, the resulting CD4+ thymocyte clones produced TNF-beta, IFN-gamma, and IL-10 in addition to IL-4 and IL-5. These results suggest that CD4+ human thymocytes have the potential to develop into cells producing the Th2 cytokines IL-4 and IL-5, whereas the ability to produce both Th1 cytokines and IL-10 is acquired only after priming with IL-12.

An immunoglobulin E-dependent recombinant histamine-releasing factor induces interleukin-4 secretion from human basophils

A novel recombinant histamine-releasing factor (rHFR), which stimulates secretion from a subpopulation of human basophils that express a particular type of immunoglobulin E (IgE) or IgE+, was found to induce interleukin-4 (IL-4) production from cells isolated from these same donors. The secretion of IL-4 protein induced by rHRF significantly correlated with histamine release and the amount of protein generated, and the kinetics were identical to those caused by anti-IgE activation. Furthermore, the ability of rHRF to induce IL-4 protein production from cells not normally responsive to this protein was transferred by passive sensitization with plasma containing IgE+ antibody. That this novel protein stimulates both mediator release and the secretion of IL-4 protein from human basophils suggests a prominent role for this molecule in allergic disease.

Clinical management of asthma in the 1990s. Current therapy and new directions

Asthma is a serious global health problem affecting nearly 100 million people worldwide. Its rising prevalence and associated morbidity and mortality are of increasing concern. Traditionally, symptomatic control of bronchoconstriction with beta 2 agonists and theophylline has been the mainstay of therapy. However, during recent years, inflammation has been recognised as the predominant cause of reversible airway obstruction and airway hyperreactivity. As a result, the emphasis in treatment has shifted to the early use of inhaled corticosteroids to control airway inflammation. beta 2 agonists are best used on an as-needed basis for the relief of acute bronchoconstriction and for the prevention of exercise-induced asthma. Sustained release theophylline or an inhaled long-acting beta 2 agonist may effectively control nocturnal symptoms. Preliminary studies involving agents active in the 5-lipoxygenase pathway as preventive therapy are encouraging. Further studies are needed to define their role in the management of asthma.

CD40-CD40 ligand (CD40L) interactions and X-linked hyperIgM syndrome (HIGMX-1)

Interactions between the B cell surface antigen CD40 and its ligand (CD40L) expressed on activated T cells play a critical role in isotype switching. This is illustrated by failure of isotype switching in patients with X-linked hyperIgM syndrome in whom the CD40L gene is mutated and by failure of isotype switching of CD40-deficient mice in response to T-cell-dependent antigens. We review these findings and discuss the signaling mechanisms of CD40 and the developmental control and transcriptional regulation of CD40L expression.

Hydrocortisone enhances total IgE levels--but not the synthesis of allergen-specific IgE--in a monocyte-dependent manner

Recently, hydrocortisone (HC), when combined with human IL-4, has been reported to increase IgE levels in supernatants (SN) of in vitro cultured leucocytes. In this study we investigated the influence of HC on allergen-specific IgE synthesis. Moreover, we examined the relevance of different cell types in this respect. Peripheral blood mononuclear cells (PBMC), T-cell depleted PBMC, CD14-depleted PBMC and highly purified B cells from 10 allergic (birch pollen and/or grass pollen) patients and five non-allergic individuals were investigated. The cells were incubated with HC and/or recombinant human IL-4 (rIL-4) for 8 days. A considerable increase of total IgE was observed in HC/rIL-4-stimulated cultures compared with rIL-4 alone, HC alone or non-stimulated cultures. We demonstrate that this effect depends on the presence of monocytes in in vitro cultures. These results were seen in every experiment, irrespective of healthy or atopic state of the blood donor. The increase of IgE could not be attributed to a rise of birch pollen-and/or grass pollen-specific IgE in patients allergic to these allergens, as shown by IgE-immunoblot. Radio-allergosorbent test (RAST) investigations of HC/rIL-4-stimulated cells cultures from allergic and non-allergic patients confirmed that HC/rIL-4-induced elevated IgE production was also not due to increased production of IgE, specific for important aero-allergens (pollens, house dust mite or animal dander). Therefore we conclude that newly synthesized IgE is not specific for allergens, but that sequential isotype switching in human B cells leads to increased polyclonal IgE production.

Effect of an asthmatic attack on CD23 and CD21 expression on lymphocytes from allergic children during the allergen season

BACKGROUND

The overproduction of IgE antibodies by atopic individuals in response to inhaled aeroallergen, forms the basis of an allergic disease. Furthermore, the exposure to allergen might trigger the symptom exacerbation.

OBJECTIVE

In children with bronchial asthma, the possible effects of seasonal, natural exposure to allergen on the expression of CD21 and CD23 antigens on B lymphocytes, and on the expression of HLA-DR, CD45RA and CD45RO on CD4+ T cells investigated.

METHODS

Heparinized blood samples were obtained from 15 children with bronchial asthma allergic to Dermatophagoides pteronyssinus (Der p) at the time of an acute asthmatic attack and 2-4 weeks after the attack when the peak expiratory flow (PEF) was stabilized. The samples were analysed on a flow cytometer after the three-colour immunofluorescence staining had been performed.

RESULTS

The increased proportion of B cells expressing CD23 antigen was found at the time of attack rather than after stabilization. Serum levels of total and Der p-specific IgE increased 2-4 weeks after the asthmatic attack. This increase was accompanied by a further increase in the expression of CD23 antigen on CD21- B lymphocytes. In 10 out of 15 tested children, we found CD23 expressed on CD4+HLA-DR+ T cells during the asthmatic attack. No significant difference was found in the expression of CD45RA and CD45RO.

CONCLUSION

Since we have previously demonstrated the increased percentage of CD23 on CD21- B cells in allergic children as compared with controls, we speculate that natural exposure to the allergen which caused the increase in total and specific IgE levels might be related to the increased expression of CD23 on CD21- B cells.

Methylation patterns of I epsilon region in B cells stimulated with interleukin 4 and Epstein-Barr virus in patients with a high level of serum IgE

Human IgE synthesis requires the presence of both interleukin 4 (IL-4) and T-cells. However, it is not clear what role IL-4 and T-cells play in the induction of IgE synthesis at the level of gene regulation. B cells that were obtained from patients with a high level of serum IgE and from healthy donors were immortalized by Epstein-Barr virus. We examined IgE production of these B cells stimulated with IL-4. Supernatant IgE levels of patient's B cells cultured with or without IL-4 were higher than those of healthy donor's B cells. Our results indicated that B cells stimulated with IL-4 from patients produced IgE, germline C epsilon transcript, and S mu S epsilon recombination. The germline C epsilon transcript was dose-dependently induced in the presence of IL-4 and related to the supernatant IgE level. In B cell stimulated with IL-4 that were obtained from patients, (some of the) DNA near or within the I epsilon region was (already partly) unmethylated, unlike those from healthy donors, and there was a loss of methyl groups of the DNA upon the addition of IL-4 in B cells from both patients and normal donors. IgE synthesis of B cells stimulated with IL-4 in patients with a high level of serum IgE is due to an accessibility in the immunoglobulin heavy-chain isotype switch, and this may reflect the accessibility in synthesis of germline C epsilon transcript, which may be caused by the increase of opening chromatin structures because of their unmethylation in the I epsilon region.

Effect of rhinovirus 39 (RV-39) infection on immune and inflammatory parameters in allergic and non-allergic subjects

The economic impact and medical complication rate of the common cold are well documented, but many of the physiological, inflammatory, and immune responses to common cold viruses have only recently been investigated. The purpose of this study was to compare selected systemic immune and inflammatory responses to experimental rhinovirus (RV)-39 challenge in seronegative allergic rhinitis and non-allergic rhinitis subjects. Peripheral blood was obtained before (baseline), during (acute), and 23 days after (convalescent) RV-39 intranasal challenge and assayed for leucocyte histamine release, serum immunoglobulins, allergen-specific IgE antibodies, plasma histamine, and platelet aggregation. All subjects were infected, as manifested by viral shedding in nasal secretions or seroconversion. RV-39 infection induced significant acute increases in serum IgE, leucocyte histamine release, and platelet aggregation, but caused no changes in serum IgG, serum IgA, serum IgM, and plasma histamine. The first change was confined to the allergic rhinitis subjects. There was no evidence that the acute rise in total serum IgE was due to an elevation of a pre-existing, pollen-specific serum IgE antibody. The results show that intranasal challenge with RV-39 induced changes in systemic immune and inflammatory parameters with a unique response pattern in allergic rhinitis subjects.

Co-stimulation of T cells via CD28 inhibits human IgE production; reversal by pertussis toxin

In lymphocyte cultures, IgE production was achieved by stimulating T cells with anti-CD2 and IL-2. Here we show that anti-CD28, in the presence or absence of IL-2, reduces this IgE production approximately 10-fold. This inhibition of IgE production was almost completely reversed by Pertussis toxin (PT). PT had no effect on IgE production when the cells were stimulated in the absence of anti-CD28. No major effects of PT were found on IgM production. PT had no effect on purified B cells, stimulated with IL-4 and anti-CD40. In the presence of saturating amounts of rIL-4 similar results were obtained, albeit the absolute amounts of IgE produced were higher in all situations. Furthermore, PT-induced IgE production was still dependent on IL-4, as was evident from experiments in which anti-IL-4 was added to the culture. The IgE enhancing effect was dependent on the adenosine diphosphate (ADP)-ribosyltransferase activity of PT, because a mutant molecule lacking this activity was not able to restore anti-CD28-induced inhibition of IgE synthesis. Thus, we show that co-stimulation with anti-CD28 causes an inhibition of T cell-dependent IgE production by B cells, which inhibition can be specifically overcome by PT. An analysis of the molecular pathways underlying this phenomenon may contribute to our understanding of the regulation of IgE synthesis in (patho)physiological conditions.