In vitro studies of human ragweed allergy: changes in cellular and humoral activity associated with specific desensitization

Subcutaneous allergen immunotherapy in the treatment of allergic respiratory disease

Subcutaneous immunotherapy is recognized as a cornerstone in the management of allergic respiratory disease in patients who are properly characterized with allergy and with allergic rhinoconjunctivis and/or well-controlled asthma, and who are willing to adhere to the rigorous treatment program. A key tenet is that it affords the opportunity to effect long-term clinical remission through its disease-modifying properties. Furthermore, it has the potential to prevent the progression of allergic rhinitis to asthma, prevent new allergen sensitivities, and improve a patient's quality of life.

The role of allergen-specific IgE, IgG and IgA in allergic disease

Immunoglobulin E (IgE)‐mediated allergy is the most common hypersensitivity disease affecting more than 30% of the population. Exposure to even minute quantities of allergens can lead to the production of IgE antibodies in atopic individuals. This is termed allergic sensitization, which occurs mainly in early childhood. Allergen‐specific IgE then binds to the high (FcεRI) and low‐affinity receptors (FcεRII, also called CD23) for IgE on effector cells and antigen‐presenting cells. Subsequent and repeated allergen exposure increases allergen‐specific IgE levels and, by receptor cross‐linking, triggers immediate release of inflammatory mediators from mast cells and basophils whereas IgE‐facilitated allergen presentation perpetuates T cell–mediated allergic inflammation. Due to engagement of receptors which are highly selective for IgE, even tiny amounts of allergens can induce massive inflammation. Naturally occurring allergen‐specific IgG and IgA antibodies usually recognize different epitopes on allergens compared with IgE and do not efficiently interfere with allergen‐induced inflammation. However, IgG and IgA antibodies to these important IgE epitopes can be induced by allergen‐specific immunotherapy or by passive immunization. These will lead to competition with IgE for binding with the allergen and prevent allergic responses. Similarly, anti‐IgE treatment does the same by preventing IgE from binding to its receptor on mast cells and basophils. Here, we review the complex interplay of allergen‐specific IgE, IgG and IgA and the corresponding cell receptors in allergic diseases and its relevance for diagnosis, treatment and prevention of allergy.

Monitoring Allergen Immunotherapy Effects by Microarray

Allergen-specific immunotherapy (AIT) is the only treatment of IgE-mediated allergies so far that has a sustained effect on clinical symptoms and can modify the course of the disease. It is an allergen-specific treatment and therefore requires the correct identification of the disease-causing allergens. Furthermore, AIT is a time-consuming treatment for which the efficacy is dependent on several factors. Therefore, diagnostic tests and biomarkers are needed that facilitate (1) selection of the correct allergens according to the patient's individual sensitization profile and (2) to monitor the effects of AIT. This can provide support for the decision to continue, modify, or discontinue vaccination. One significant mechanism of action of AIT is the induction of allergen-specific antibodies that compete with IgE for the binding to allergen molecules, hence referred to as blocking antibodies. It was shown in several studies that the induction of blocking antibodies by AIT, and their specificity can be measured by allergen microarrays. Inhibition of allergen-specific IgE binding by blocking antibodies can also be determined by microarrays and is associated with changes in clinical parameters or other in vivo and in vitro assays demonstrating efficacy of AIT. Furthermore, allergen microarrays allow determination of IgE sensitizations towards a comprehensive set of allergen molecules and therefore are well suited for identifying the disease-causing allergens for correct prescription of AIT. Thus, diagnostic tests based on microarrayed allergens can be useful in determining the correct prescription of AIT and can be used to monitor efficacy of AIT.

Critical appraisal of Timothy grass pollen extract GRAZAX in the management of allergic rhinitis

Allergic rhinitis is one of the most common diseases of adult and pediatric age, associated with grass pollen (GP) allergy in >50% cases, with a consistent impact on quality of life of affected patients. A grass allergen tablet, containing standardized extract derived from Timothy grass (Phleum pratense) pollen and ~15 μg major allergen P. pratense (rPhl p 5), may be the future of allergen-specific immunotherapy (IT) for GP allergy. The aim of this review was to critically evaluate the role of Timothy GP extract IT for the management of allergic rhinitis. For this purpose, we have tried to analyze potential mechanisms of action at the basis of Timothy GP extract, we have reviewed efficacy studies to establish potential benefits and clinical response, and we have also evaluated safety and tolerability profiles and patient focus perspective, such as quality of life, satisfaction and acceptability, and compliance to this IT.

Randomized controlled trial of a ragweed allergy immunotherapy tablet in North American and European adults. J Allergy Clin Immunol. 2013;131:1342-9.e6. [PMID: 23622121 DOI: 10.1016/j.jaci.2013.03.019]

BACKGROUND

In North America and Europe, millions of patients experience symptoms of allergic rhinitis with or without conjunctivitis (AR/C) on exposure to ragweed pollen. The disease burden can be significant, with most patients relying on symptomatic medications without disease-modifying potential. However, novel sublingual immunomodulatory treatment options may potentially play an important role if efficacy and side effect profiles allow the convenience of self-administration.

OBJECTIVES

This study evaluated an allergy immunotherapy tablet (AIT; SCH 39641/MK-3641) for treatment of ragweed-induced AR/C in the first large randomized, double-blind multinational trial of this therapeutic modality for ragweed allergy.

METHODS

Adults (n = 784) with short ragweed-induced AR/C were randomly assigned to approximately 52 weeks of daily self-administered ragweed AIT of 1.5, 6, or 12 units of Ambrosia artemisiifolia major allergen 1 (Amb a 1-U) or placebo. Subjects could use as-needed allergy rescue medication. Symptoms and medications were recorded daily. The primary efficacy end point was total combined daily symptom/medication score (TCS) during peak ragweed season. Safety was monitored through adverse event diaries maintained through study duration.

RESULTS

During peak ragweed season, ragweed AIT of 1.5, 6, and 12 Amb a 1-U reduced TCS by 9% (-0.76; P = .22), 19% (-1.58; P = .01), and 24% (-2.04; P = .002) compared with placebo. During the entire season, ragweed AIT of 1.5, 6, and 12 Amb a 1-U reduced TCS by 12% (-0.88; P = .09), 18% (-1.28; P = .01), and 27% (-1.92; P < .001) compared with placebo. Treatment was well tolerated; no systemic allergic reactions occurred.

CONCLUSIONS

In this trial, ragweed AIT of 12 Amb a 1-U was effective and tolerable with a safety profile that permitted daily self-administration of ragweed allergen immunotherapy.

Allergen-specific immunotherapy in allergic rhinitis and asthma. Mechanisms and proof of efficacy

Appeared at the beginning of the 20th century, allergen-specific immunotherapy (SIT) has long been used in allergic rhinitis and asthma without any knowledge of its mechanisms of action or any tangible proof of its efficacy. However, from the beginning of the era of evidence-based medicine, a number of placebo-controlled studies have been published and reached a sufficient number to assess the cellular events induced by SIT and allow meta-analysis to provide guidelines based on proofs. Controlled studies and meta-analysis concerned not only subcutaneous immunotherapy but also the sublingual route, demonstrating an effect of SIT on symptoms and medication use. Most recently sublingual tablets were proposed in allergic rhinitis. This paper reviews the mechanisms of SIT, the evidence of efficacy of SIT from the injective to the sublingual route and reminds the current guidelines.

Injection and sublingual immunotherapy in the management of allergies affecting the unified airway

The spectrum of allergic disease involves both the upper and lower airways. Immunotherapy has been shown to produce immunologic changes that can result in the improvement of allergic diseases. Numerous clinical trials have demonstrated the effectiveness of injection and sublingual immunotherapy in the treatment of rhinitis and asthma. Recent data suggest that immunotherapy may have a role in preventing the development of new sensitizations or in decreasing the progression of allergic disease from rhinitis to asthma. Models of immunotherapy may therefore transition from symptom-relieving treatments to preventive methodologies for the management of allergic disease.

Immunologic analysis of monoclonal and immunoglobulin E antibody epitopes on natural and recombinant Amb a 1

BACKGROUND

Amb a 1 is the major allergen from ragweed pollen and more than 90% of ragweed-allergic patients react with this protein. Although Amb a 1 was cloned and sequenced in 1991, little is known of the specificity of anti-Amb a 1 antibodies or of the immunologic properties of the recombinant allergen.

OBJECTIVE

To compare binding of monoclonal antibodies (mAb) and IgE antibodies to purified natural Amb a 1 (nAmb a 1) and recombinant Amb a 1 (rAmb a 1).

METHODS

Binding of a panel of anti-Amb a 1 mAb and IgE antibodies to nAmb a 1 or rAmb a 1 was compared by immunoblotting. Chimeric ELISA was used to measure specific IgE to these allergens using 89 ragweed-allergic sera from Austria, Italy, Canada and the United States.

RESULTS

The 8 mAb bound to a 38 kDa Amb a 1 band in ragweed pollen extract and a subset of 5 mAb also bound to the 26 kDa chain of nAmb a 1. A two-site ELISA was developed using a mAb pair, which was approximately 10-fold more sensitive to rAmb a 1. There was a significant correlation between IgE antibody binding to nAmb a 1 and rAmb a 1 (n=89, r=0.79, P<0.001). A subset of approximately 40% of patients showed greater reactivity to nAmb a 1 than to rAmb a 1.

CONCLUSIONS

The data suggest that there is less reactivity of human IgE to rAmb a 1 compared with nAmb a 1. The development of more sensitive, quantitative ELISA for Amb a 1 will require the production of new mAb especially directed against nAmb a 1.

Mechanisms of immunotherapy in allergic rhinitis

Allergic rhinitis is a common condition, but many people still experience suboptimal control of symptoms despite measures such as allergen avoidance, intra-nasal steroids and antihistamines. Specific immunotherapy (SIT) has been used for many years, but though many studies show clinical efficacy, its mechanism of action is still not clearly understood. Earlier studies showed changes in antibodies and it may be that SIT works through mechanisms that alter the ratio of 'protective' IgG4 to 'pro-allergenic' IgE. Other studies have shown a reduction in eosinophil migration to nasal mucosa as well as a reduction in inflammatory mediator release including basophil histamine release. More recent studies have proposed that SIT works through inhibition of T-helper 2 lymphocytes (Th2) which preferentially produce cytokines that promote allergic responses. SIT may cause a deviation from Th2 to Th1 (T-helper 1 lymphocytes) or may induce T-regulatory cells (T-regs) which inhibit Th2 responses directly or through inhibitory cytokines.

Immunotherapy with a ragweed-toll-like receptor 9 agonist vaccine for allergic rhinitis

BACKGROUND

Conjugating immunostimulatory sequences of DNA to specific allergens offers a new approach to allergen immunotherapy that reduces acute allergic responses.

METHODS

We conducted a randomized, double-blind, placebo-controlled phase 2 trial of a vaccine consisting of Amb a 1, a ragweed-pollen antigen, conjugated to a phosphorothioate oligodeoxyribonucleotide immunostimulatory sequence of DNA (AIC) in 25 adults who were allergic to ragweed. Patients received six weekly injections of the AIC or placebo vaccine before the first ragweed season and were monitored during the next two ragweed seasons.

RESULTS

There was no pattern of vaccine-associated systemic reactions or clinically significant laboratory abnormalities. AIC did not alter the primary end point, the vascular permeability response (measured by the albumin level in nasal-lavage fluid) to nasal provocation. During the first ragweed season, the AIC group had better peak-season rhinitis scores on the visual-analogue scale (P=0.006), peak-season daily nasal symptom diary scores (P=0.02), and midseason overall quality-of-life scores (P=0.05) than the placebo group. AIC induced a transient increase in Amb a 1-specific IgG antibody but suppressed the seasonal increase in Amb a 1-specific IgE antibody. A reduction in the number of interleukin-4-positive basophils in AIC-treated patients correlated with lower rhinitis visual-analogue scores (r=0.49, P=0.03). Clinical benefits of AIC were again observed in the subsequent ragweed season, with improvements over placebo in peak-season rhinitis visual-analogue scores (P=0.02) and peak-season daily nasal symptom diary scores (P=0.02). The seasonal specific IgE antibody response was again suppressed, with no significant change in IgE antibody titer during the ragweed season (P=0.19).

CONCLUSIONS

In this pilot study, a 6-week regimen of the AIC vaccine appeared to offer long-term clinical efficacy in the treatment of ragweed allergic rhinitis. (ClinicalTrials.gov number, NCT00346086 [ClinicalTrials.gov] .).

Mechanisms of allergen-specific immunotherapy: T-regulatory cells and more

Activation-induced cell death, anergy, or immune response modulation by regulatory T cells (Treg cells) are essential mechanisms of peripheral T-cell tolerance. Genetic predisposition and environmental instructions tune thresholds for the activation of T cells, other inflammatory cells, and resident tissue cells in allergic diseases. Skewing allergen-specific effector T cells to a Treg-cell phenotype seems to be crucial in maintaining a healthy immune response to allergens and successful allergen-specific immunotherapy. The Treg-cell response is characterized by an abolished allergen-specific T-cell proliferation and the suppressed secretion of T-helper 1- and T-helper 2-type cytokines. Suppressed proliferative and cytokine responses against allergens are induced by multiple suppressor factors, including cytokines such as interleukin-10 (IL-10) and transforming growth factor beta (TGF-beta), and cell surface molecules such as cytotoxic T-lymphocyte antigen-4, programmed death-1, and histamine receptor 2. The increased levels of IL-10 and TGF-beta produced by Treg cells potently suppress IgE production while simultaneously increasing the production of noninflammatory isotypes IgG4 and IgA, respectively. In addition, Treg cells directly or indirectly suppress the activity of effector cells of allergic inflammation, such as mast cells, basophils, and eosinophils. In conclusion, peripheral tolerance to allergens is controlled by multiple active suppression mechanisms on T cells, regulation of antibody isotypes, and suppression of effector cells. The application of current knowledge of Treg cells and related mechanisms of peripheral tolerance may soon lead to more rational and safer approaches to the prevention and cure of allergic disease.

Mechanisms of allergen specific immunotherapy--T-cell tolerance and more

Specific immune suppression and induction of tolerance are essential processes in the regulation and circumvention of immune defence. The balance between allergen-specific T-regulatory (Treg) cells and T helper 2 cells appears to be decisive in the development of allergic and healthy immune response against allergens. Treg cells consistently represent the dominant subset specific for common environmental allergens in healthy individuals. In contrast, there is a high frequency of allergen-specific T helper 2 cells in allergic individuals. A decrease in interleukin (IL)-4, IL-5 and IL-13 production by allergen-specific CD4+ T cells due to the induction of peripheral T cell tolerance is the most essential step in allergen-specific immunotherapy (SIT). Suppressed proliferative and cytokine responses against the major allergens are induced by multiple suppressor factors, such as cytokines like IL-10 and transforming growth factor (TGF)-beta and cell surface molecules like cytotoxic T lymphocyte antigen-4, programmed death-1 and histamine receptor 2. There is considerable rationale for targeting T cells to increase efficacy of SIT. Such novel approaches include the use of modified allergens produced using recombinant DNA technology and adjuvants or additional drugs, which may increase the generation of allergen-specific peripheral tolerance. By the application of the recent knowledge in Treg cells and related mechanisms of peripheral tolerance, more rational and safer approaches are awaiting for the future of prevention and cure of allergic diseases.

Is immunotherapy-induced birch-pollen-specific IgG4 a marker for decreased allergen-specific sensitivity?

BACKGROUND

The role of IgG4 during allergen-specific immunotherapy (SIT) is still controversial. The available studies present paramount differences in in vitro techniques, allergens, and clinical outcome parameters. By implementing a sensitive method, and pivotal clinical outcome parameters, we wanted to ascertain the utility of IgG4 as a clinical marker of decreased allergen-specific sensitivity to a common aeroallergen.

METHODS

Sera were drawn from 23 birch-pollen-allergic patients during a placebo-controlled clinical trial on birch pollen SIT. Seventeen patients received active treatment. Blood samples were drawn at 0, 2, 4, 7, and 30 treatment weeks, and 36 months. The binding activity of autologous IgG, IgG4, IgE, and IgE- and/or IgG-depleted serum to (125)I-labelled recombinant Bet v 1 was assessed in a fluid-phase radioimmunoassay. Disease severity was assessed subjectively on a visual analogue scale (VAS), and objectively by intradermal late-phase reaction diameters.

RESULTS

Before SIT IgG4 fraction of IgG-allergen binding varied from 4 to 74%, with a median of 36%, increasing to 71% after 36 months. Changes in IgG4 or IgG4/IgG fraction were not correlated to clinical outcome parameters. Changes in IgG allergen binding and VAS were significantly correlated (sigma = 0.72; p < 0.05). SIT increased the serum-blocking activity of IgE allergen binding from 25% before SIT to 80% after SIT. No changes were observed in the placebo group.

CONCLUSION

The data suggest that IgG4 per se is a poor marker of decreased allergen-specific sensitivity to birch pollen, both as a single measurement and as delta values.

Expression of interleukin 4 receptors in bronchial asthma patients who underwent specific immunotherapy

BACKGROUND

Interleukin (IL) 4 and IL-13 are crucial cytokines for the development of allergic reactions and have been shown to modulate the function of monocytes and macrophages.

OBJECTIVES

To evaluate the expression of IL-4Rs on peripheral blood monocytes and in the serum of patients with bronchial asthma who underwent specific immunotherapy (SIT).

METHODS

The study was performed on 17 asthma patients with a typical clinical history and positive skin prick test results to Dermatophagoides pteronyssinus allergens. Five asthma patients who declined SIT were used as a comparator control group. Ten healthy persons served as negative controls. Flow cytometry analysis was performed on the whole blood samples using labeled monoclonal antibodies against CD14 and CD36 monocyte markers and against the CD124 alpha chain of IL-4R. The serum levels of soluble IL-4R were evaluated using an immunoenzymatic assay.

RESULTS

Compared with controls, bronchial asthma patients before SIT had a higher mean +/- SD percentage of CD14-positive cells that coexpressed CD124 (3.5% +/- 1.8% vs 18.6% +/- 7.9%; P < .01). After SIT, the mean +/- SD percentage of CD14 cells coexpressing CD124 decreased to 8.1% +/- 5.1%, which was significantly lower than before SIT (P < .01) but still significantly higher than in controls (P = .01). Changes in CD124 expression were associated with up-regulation of CD14 and down-regulation of CD36 expression on peripheral blood monocytes, suggesting that IL-4/IL-13-mediated signaling may be important for regulation of monocyte phenotype and function in asthma patients receiving SIT.

CONCLUSIONS

Even short courses of SIT are associated with a decrease in IL-4R expression on peripheral blood monocytes, which may cause decreased IL-4/IL-13-mediated effects in patients who undergo SIT.

Does allergen immunotherapy alter the natural course of allergic disorders?

Allergy in patients with atopy is caused by clinical adverse reactions to environmental antigen, which is often associated with allergen-specific immunoglobulin (Ig)E production. Since allergy reflects an inappropriate immunological reaction, a therapeutic approach related to immunology is likely to actively alter the natural course of allergic disorders. Allergen immunotherapy, known at various times as desensitisation or hyposensitisation, is very recently defined by the World Health Organization as therapeutic vaccines for allergic diseases. At present, it has become a common clinical practice in selected patients for the treatment and prevention of the recurrence of allergic disorders caused by insect venoms and has proven to be effective in changing the course of allergic responses induced by grass and tree pollen, animal hair and dander, house dust mite and mold, as demonstrated by improvement in clinical symptoms, skin prick test and medication scores. Reported effects of allergen immunotherapy on the natural course of allergic disorders include (i) prevention of reaction following re-sting in insect venom allergy; (ii) prevention or decrease the rate of the natural progress of allergic rhinitis to asthma; and (iii) inhibition of new sensitisation in monosensitised children. Many aspects of the immune responses associated with allergic disorders, including antibody production, cytokine secretion, T cell activation and local inflammatory reactions, are found to be significantly altered during and/or after immunotherapy. Specifically, the ratio of allergen-specific IgG4 to IgG1 correlates well with positive clinical outcome caused by allergen immunotherapy in patients with pollen-allergy. Allergen immunotherapy affects the cytokine profile of allergen-specific T cells and switches T(H)2 type immune responses in patients with atopy towards T(H)0 or T(H)1 type responses. Although the changes in the absolute value of T(H)1 or T(H)2 cytokines appear quite variable, the increase in the ratio of T(H)1/T(H)2 cytokines is very consistent among published reports, especially in the late stage of treatment. Accumulating evidence indicates that appropriate immunotherapy prevents the onset of new sensitisation and prevents the progress of allergic rhinitis to asthma. Although the changes in B cell and T cell responses, especially IgG antibodies and T(H)1/T(H)2 cytokine production, may be the major mechanism underlying the clinical efficacy of allergen immunotherapy and the prevention of the development of allergic phenotypic changes, multiple mechanisms may be involved in the outcome of alteration of the natural course of allergic disorders.

The consideration of immunotherapy in the treatment of allergic asthma

BACKGROUND

Immunotherapy (IT) has undergone rigorous trials to evaluate its therapeutic benefit in the treatment of allergic respiratory disease. The tools of molecular biology have provided a framework with which to begin to understand the mechanistic effects of IT on the underlying inflammatory component of allergic respiratory disease.

RESULTS

The clinical relevance of these observations belies our understanding of allergic inflammation as the subsoil for the development of abnormal airway physiology, heightened bronchial reactivity, and the development of chronic asthmatic symptomatology.

CONCLUSIONS

IT provides the potential to downregulate this inflammatory cascade, reduce IgE antibody production, and attenuate symptoms. Conceptually, early intervention of allergic disease holds the most promise as a therapeutic intervention capable of arresting the progression of the disease, altering the severity of the disease, and/or preventing the development of the respiratory disease process.

The consideration of immunotherapy in the treatment of allergic asthma

Immunotherapy has undergone rigorous trials to assess its therapeutic benefit in the treatment of allergic respiratory disease. The tools of molecular biology have provided a framework with which to begin to understand the mechanistic effects of immunotherapy on the underlying inflammatory component of allergic respiratory disease. The clinical relevance of these observations belies our understanding of allergic inflammation as the subsoil for the development of abnormal airway physiology, heightened bronchial reactivity, and the development of chronic asthmatic symptoms. Immunotherapy provides the potential to downregulate this inflammatory cascade, reduce IgE antibody production, and attenuate symptoms. Conceptually, early intervention of allergic disease holds the most promise as a therapeutic intervention capable of arresting the progression of the disease, altering the severity of the disease, and/or preventing the development of the respiratory disease process.

Guidelines for the use of allergen immunotherapy. Canadian Society of Allergy and Clinical Immunology

OBJECTIVES

To recommend guidelines for the use of allergen immunotherapy to treat allergies in patients for whom allergen avoidance and drug therapy have not been sufficiently effective.

OPTIONS

High-dose or low-dose allergen immunotherapy for the treatment of IgE-mediated allergy to insect stings, allergic rhinoconjunctivitis and asthma.

OUTCOMES

Clinical evaluation of symptoms, objective measurement of reactions to nasal or bronchial allergen challenge, immunologic changes as a result of allergen immunotherapy and, among patients with anaphylactic reactions to stinging insects, clinical outcome of intentional sting challenge.

EVIDENCE

A search of MEDLINE was conducted to identify articles that presented results of allergen immunotherapy. Proceedings of symposia held by international subcommittees and of consensus meetings, as well as references obtained from these sources, were reviewed. The articles were grouped according to their main subject: immunologic effects, specific allergies, the results of randomized placebo-controlled clinical trials, types of allergen extract and protocols for allergen immunotherapy, adverse effects and deficiencies of allergen immunotherapy.

VALUES

Each member of the working group assessed the importance of such issues as basic immunologic effects, clinical efficacy, adverse effects and inappropriate use; the working group then arrived at a consensus.

BENEFITS, HARMS AND COSTS

Implementation of these guidelines would lead to the appropriate use of allergen immunotherapy and control inappropriate treatment, which could result in adverse effects and increased costs of services for patients with allergies.

RECOMMENDATIONS

Allergen immunotherapy with specific, standardized allergenic materials, administered in high-dose schedules, is effective in patients with an allergy to insect stings or allergic rhinoconjunctivitis, and in some patients with asthma, who have been correctly diagnosed through a meticulous history corroborated by positive results of skin tests and for whom avoidance of the allergen and drug therapy are not sufficiently effective.

VALIDATION

These guidelines are similar to others being developed in the United States and recommended by the Joint Council of Allergy and Immunology and the American Academy of Allergy, Asthma and Immunology.

SPONSOR

These guidelines were developed by a working group of the Canadian Society of Allergy and Clinical Immunology; no funding was received from any other source.

A reduction in allergen-induced Fc epsilon R2/CD23 expression on peripheral B cells correlates with successful hyposensitization in grass pollinosis

BACKGROUND

The cellular basis for the mechanism of specific hyposensitization is still unclear.

OBJECTIVE

We prospectively studied the effect of immunotherapy on allergen-induced proliferation and Fc epsilon R2/CD23 expression of lymphocytes.

METHODS

Mononuclear cells prepared from the peripheral blood of 22 patients with grass pollen (GP) allergy before, during, and after a preseasonal immunotherapy period with GP were stimulated with GP or control antigens. Tritiated thymidine uptake and percentage of CD23+ B cells were determined daily during days 6 to 8 and compared with lymphocyte responsiveness of 11 only symptomatically treated atopic patients and 14 nonatopic individuals.

RESULTS

GP-induced lymphocyte proliferative response of both hyposensitized and symptomatically treated GP-allergic patients decreased markedly before the pollen season and rose again after seasonal allergen exposure, whereas a long-lived decrease in GP-induced Fc epsilon R2/CD23+ B cells was only observed in GP-treated patients. Alterations in Fc epsilon R2/CD23 expression were closely related to changes in symptoms and medication requirement during the following pollen season. In contrast, immunotherapy had no effect on Fc epsilon R2/CD23 expression of B cells without stimulation or on B cells cultured in the presence of control antigens.

CONCLUSION

Because Fc epsilon R2/CD23 expression on B cells is antagonistically regulated by the cytokines interleukin-4 and interferon-gamma, the decrease of allergen-induced Fc epsilon R2/CD23+ B cells indicates an altered cytokine secretion pattern of the allergen-specific T lymphocytes with a predominance of interferon-gamma.

Regulation of the human immune response to ragweed pollen by immunotherapy. A controlled trial comparing the effect of immunosuppressive peptic fragments of short ragweed with standard treatment

A new allergenic preparation consisting of peptic fragments of short ragweed has been tested for its clinical effectiveness. Such enzymatically derived fragments have been shown in prior murine studies to retain the T epitopes of the original allergen but to have a severe reduction in the number of B epitopes. Three groups of ragweed hayfever patients were placed on pre-seasonal immunotherapy. One group received a conventional ragweed preparation that had been enriched for antigen E (Amb a I), designated as Pool 2. The second group was given fragments of Pool 2 (fSRW) prepared by peptic digestion and the third group was injected with histamine as a placebo. Groups treated with the fSRW and Pool 2 had significantly reduced symptom-medication scores compared with the placebo-treatment group. However, fSRW-treated patients fared significantly better than Pool 2 patients (P less than 0.02). fSRW injections caused a significant rise in preseasonal specific IgG, antibodies as well as suppression of the seasonal anamnestic specific IgE increase. Similar, but not quite as marked changes occurred with Pool 2 treatment. fSRW was well tolerated and non-toxic. Thus, allergen modification by enzymatic degradation, as demonstrated here, appears to be a promising new approach for allergen immunotherapy.

Changes in nasal metachromatic cells during allergen immunotherapy

We have investigated changes of nasal metachromatic cell number, nasal symptoms and nasal provocation at the third and sixth month during allergen immunotherapy. Twenty-five subjects with perennial allergic rhinitis (house dust (23), Alternaria (2) were divided into two groups: an immunotherapy-treated group (n = 14) and a control group (n = 11). At the first visit nasal symptom scores, nasal provocation reactions and the number of metachromatic cells in nasal mucosal epithelial scrapings were not significantly different between groups. At the third and sixth month after immunotherapy nasal symptom scores, nasal provocation and the metachromatic cells in epithelial scrapings were significantly reduced (P less than 0.05) compared with the pretreatment values in the immunotherapy group, but unchanged in the control group. These results suggest that the reduction in metachromatic cell number at the nasal mucosal surface may be one of the mechanisms which could explain the improvement of nasal allergic symptoms by immunotherapy.

Immune mechanisms in allergen-specific immunotherapy

Allergen-specific immunotherapy has been shown to be clinically effective in patients with seasonal allergic rhinitis and/or asthma. Patients who receive this therapy undergo a number of specific immunologic changes in response to the allergen being administered. These include a "blunting" of the seasonal rise of allergen-specific IgE as well as lowering baseline IgE levels, generation of an allergen-specific IgG response, development of auto-anti-idiotypic antibodies, reduced basophil histamine release in response to allergen, decreased lymphocyte proliferation, lymphokine production in response to allergen, and the generation of allergen-specific suppressor T cells that down-regulate lymphoproliferative responses and IgE synthesis. The mechanism by which allergen-specific immunotherapy produces clinical efficacy is not known. Recent evidence suggests that the development of immunoregulatory responses (suppressor T cells and anti-idiotypic antibodies) during immunotherapy may account for the immunologic changes described above but as yet have not been correlated with clinical outcome. Identification of epitopes on allergens that can induce selective T helper/suppressor responses may provide opportunities for producing immunological tolerance and a reduction in the allergic diathesis.

Responses to ragweed-pollen nasal challenge before and after immunotherapy

To evaluate whether immunotherapy reduces mediator release after nasal challenge, we followed previously untreated patients with ragweed hay fever through 2 years (three seasons) of treatment. Eleven adult patients started immunotherapy after a season of symptom diaries and graded pretreatment challenges with 0.03, 0.3, 3.3, and 16.5 mg of ragweed pollen. Repeat challenges were performed when the treatment dosage reached 0.6, 12.4, and 24.8 micrograms of Amb a I (antigen E) equivalents per injection. After the 0.6 micrograms dose, there was little change, but after the larger doses, there was a significant reduction in histamine and tosylarginine methyl ester-esterase (TAME-esterase) release in two respects. More pollen was required before any mediator appeared, and the amount of mediator released at each stage of the challenge was reduced. There was no significant difference between the responses at the 12.4 and 24.8 micrograms treatment doses. Sneezing after challenge was not apparently changed after immunotherapy; however, patients' seasonal symptom-medication scores were reduced after treatment. These data set the optimal individual treatment dose of ragweed extract for immunotherapy at greater than 0.6 micrograms, but probably not more than 12.4 micrograms in terms of Amb a I equivalents.

Allergy shots for hay fever

Although allergy shots have been used for many years, immunotherapy for symptoms of allergic rhinitis has only recently been clearly shown to be effective. Standardization of allergens will provide even better results in the diagnosis and treatment of allergic rhinitis in the future. Success in an individual patient depends on appropriate application. Immunotherapy should be reserved for patients who have allergy to airborne allergens, have significant symptoms after exposure to them, have sensitivity that has been proven by a skin or in vitro test, and cannot avoid the allergen or control symptoms with drugs. Thus, allergy shots are generally not used for allergy to pet dander or food. Immunotherapy is begun with a very dilute concentration of allergen, which is gradually increased to the maximum dose that is safely tolerated. The interval between shots is then increased gradually to once a month. Duration of treatment is usually 3 years in children and longer in adults. Treatment usually fails if the patient cannot free the environment of large amounts of known allergens, if the allergen was not correctly determined during initial evaluation, or if the allergen dose is inadequate. The patient must have realistic expectations: Allergy shots often do not totally eliminate symptoms, and improvement takes time.

Immunological response to immunotherapy for immediate hypersensitivity: clinical relevance

Immunotherapy, also called desensitization, is effective in treating allergic rhinitis, insect sting venom hypersensitivity and probably allergic asthma. Administration of gradually increasing doses of the sensitizing antigen induces several immunological changes. The humoral responses include an increase in specific IgG titer, a decrease in specific IgE titer with blunting of its seasonal rise, and an increase in the specific anti-idiotype antibody titer. Cellular changes include diminished responsiveness of the patient's lymphocytes to stimulation by allergen as measured by thymidine incorporation. This is accounted for by the generation of suppressor cells specific for the allergen. These suppressor cells also induce suppression of IgE production by mononuclear cells. An additional effect that is attributed to IT is a decrease in basophil sensitivity to the allergen as measured by histamine release. The clinical correlates of these changes are not clear. Currently, none of the responses can be used as a tool for assessing the response in the treated individual patient. Although the increase in specific IgG was shown to correlate with the clinical response in patient groups, it is not applicable to the individual patient. Currently the best parameter for assessing clinical response is probably the increase in the ratio between the specific IgG and the specific IgE. However further studies are warranted to evaluate the significance of the change in anti-idiotype antibodies, basophil histamine release and perhaps immunological changes yet to be discovered.

Measurement of IgG blocking antibody in human serum: comparison of ELISA with monoclonal antibody and fluorogenic substrate and Staphylococcus protein A solid-phase RIA

We compared ELISA with mouse monoclonal antihuman gamma-chain antibody and a fluorogenic substrate with the Staphylococcus protein A solid-phase radioimmunoassay (SPRIA) in the measurement of specific IgG antibody to short ragweed pollen. Sera from 51 ragweed-allergic patients undergoing allergen immunotherapy were evaluated for ragweed-specific IgG antibodies with the same ragweed extract in the two assay systems. With optimal conditions, the ELISA and SPRIA displayed comparable positive thresholds (approximately 1 ng/ml of ragweed-specific IgG). Both assays also demonstrated consistently parallel dilution curves with 51 sera (mean interdilutional coefficient of variation [CV] less than 8.8% for ELISA and less than 8.6% for SPRIA). Reproducibility was determined by constructing precision profiles for intra- and interassay variations over the working ranges of each assay (ELISA, 0.8 to 100 ng/ml; SPRIA, 1 to 250 ng/ml). ELISA intra-assay CVs ranged from 13% near threshold to less than 5% at higher antibody concentrations; SPRIA intra-assay CVs ranged from 4.3% to 2.8%. Interassay reproducibility was somewhat better for SPRIA (4.6% to 9.6%) than for ELISA (10% to 18%). In direct comparison, 41 (80%) of the 51 sera were concordant in the two assays (r = 0.91; p less than 0.001). Although each assay result was reproducible, 10 (20%) of the sera elicited consistently discrepant results in the two assays. In eight of the 10 discordant sera, the SPRIA results were higher than ELISA, suggesting the possibility that some ragweed allergen may be better represented on the short ragweed-pollen extract agarose than on ELISA plate wells.(ABSTRACT TRUNCATED AT 250 WORDS)

A study of the human immune response to Lolium perenne (rye) pollen and its components, Lol p I and Lol p II (Rye I and Rye II). II. Longitudinal variation of antibody levels in relation to symptomatology and pollen exposure and correction of seasonally elevated antibody levels to basal values

This study used a standardized, dialyzed, Lolium perenne (ryegrass) pollen extract and two of its well-characterized components, Lol p I (Rye I) and Lol p II (Rye II), to characterize the longitudinal variation of both IgE and IgG antibody (Ab) levels, as well as total serum IgE levels, in 20 grass-allergic subjects followed for 13 months. Ab levels declined toward a basal level just before, and increased just after, the grass-pollination season, returning to the same basal level just before the next grass-pollination season. The least complex allergen, Lol II, demonstrated the most uniform pattern of variation in both IgE and IgG Ab levels. Total serum IgE levels demonstrated the least regular pattern of variation. Grass-pollen counts were strongly correlated with symptom-medication scores for these subjects (rs = 0.87). Initial values were correlated with the rise in total IgE and IgE Ab to Lol II across the grass-pollen season. Skin test results were correlated with initial IgE Ab levels for L. perenne pollen extract and Lol II. Finally, a procedure for correcting IgE Ab levels to basal values was proposed and tested. The correction procedure, for each IgE Ab, was based on the average rise during the grass-pollination season (or average decline after the grass-pollination season) observed for all subjects with that IgE Ab.

Immunological changes after hyposensitization in house-dust-sensitive asthmatic children: a review

Patients with allergic diseases are characterized by the presence of elevated total serum IgE and specific IgE antibodies against a variety of environmental allergens. To explore the causes for augmented IgE antibody production and the working mechanisms of hyposensitization (HS), a series of studies has been conducted on house-dust-sensitive, newly diagnosed, and hyposensitized asthmatic children and normals. The specific IgE and IgG antibodies were measured by radioallergosorbent test; the lymphoproliferative capability was measured by 3H-thymidine incorporation; the allergen-specific suppressor activity was determined by the extent of house-dust-activated, interleukin-2 (IL-2)-expanded lymphocytes to suppress the allergen-induced proliferation of autologous mononuclear cells (MNC); and IL-2 was produced by stimulating MNC with allergen or phytohemagglutinin (PHA) and quantitated by its capability to support the proliferation of mouse IL-2-dependent cytotoxic T-cell line. The results showed: 1) HS was effective in 90% of patients in terms of decreased attacks and medication taken; 2) the patients were defective in suppressor T-cell function for IgE production; 3) HS was able to restore the regulatory T-cell function and increase the production of IgG-blocking antibody; and 4) IL-2 production may be used as an indicator for initiation and discontinuation of HS. Therefore, hyposensitization is an effective and specific treatment for allergic bronchial asthma and can partially correct an immunoregulatory aberration in atopic individuals.

Histamine-dependent allergy blood test. Clinical evaluation

Allergen-mediated histamine release from human leukocytes represents an important model for in vitro studies of allergic reactions. The purpose of this study was to determine whether the measurement of histamine released in allergic patients by radioenzymatic assay following mixing of their blood with common allergens represents a reliable index for diagnosis of atopic allergy. Three categories of allergens were used: 1) house dust and mite; 2) cat and dog dander; 3) trees, grasses and ragweed mixture. The presence of allergy was established by clinical history and intradermal skin testing in the study group of 150 patients. A significant allergen-mediated histamine release ranging from 4 to 65% of the total blood histamine content was observed in 96% of the patients with skin test sensitivity of greater than or equal to 3+. There was a significant correlation between skin testing and histamine release in terms of the allergens causing the response. Thus, the measurement of histamine by radioenzymatic technique following its release in blood in response to allergen challenge represents a clinically useful in vitro test for the diagnosis of atopic disease.

Nasal challenge with ragweed pollen in hay fever patients. Effect of immunotherapy

Challenge of the nasal mucosa of allergic subjects with specific allergen induces not only the expected sneezing and rhinorrhea, but also the appearance in nasal secretions of mediators commonly associated with activation of mast cells or basophils: histamine, leukotrienes, prostaglandin D2 (PGD2), kinins, and TAME ([3H]-N-alpha-tosyl-L-arginine methyl ester)-esterase. To determine whether specific immunotherapy alters mediator release in vivo, nasal pollen challenge was used to compare 27 untreated highly sensitive ragweed (RW)-allergic subjects with 12 similarly sensitive patients receiving long-term immunotherapy (3-5 yr) with RW extract (median dose, 6 micrograms RW antigen E). The two groups were equally sensitive based on skin tests and basophil histamine release. The immunized group had a diminished response as demonstrated by (a) the treated group required higher pollen doses to excite sneezing or mediator release; (b) significantly fewer subjects in the treated group released mediators at any dose (TAME-esterase [P = 0.005], PGD2 [P = 0.04]), and (c) the treated group released 3-5-fold less mediator (TAME-esterase [P = 0.01], and histamine [P = 0.02]).

Use of the enzyme-linked immunosorbent assay for measurement of allergen-specific antibodies

A sensitive and specific enzyme-linked immunosorbent assay (ELISA) for allergen-specific IgG antibodies is described. Various solid-phase supports (microtiter plates), coating procedures, binding kinetics, and presentation of allergen in the assay were investigated. Using optimal conditions the indirect ELISA, in which the allergen is coated onto the well, was capable of detecting 2.4 ng/ml specific IgG antibodies to bee venom phospholipase A2(PLA2). The sandwich ELISA, in which the allergen was immobilized via specific antibody precoated onto the well, detected 0.24 ng/ml IgG antibodies to PLA2.

Induction of antigen-specific suppressor cells in patients with hay fever receiving immunotherapy

In order to evaluate the effect of immunotherapy on subpopulations of lymphocytes, peripheral blood mononuclear cells were fractionated into T and non-T cells by incubating in anti-immunoglobulin-coated plates. T cells were further fractionated into rye grass antigen-adherent and nonadherent fractions and human serum albumin (HSA)-adherent and nonadherent fractions by incubating in rye grass antigen-coated and HSA-coated plates, respectively. The mean rye antigen-stimulated proliferative response of rye antigen-adherent fraction was significantly lower than that of rye antigen-nonadherent fraction in patients with rye grass hay fever receiving immunotherapy. There was no difference in the rye antigen-stimulated proliferative response between the HSA-adherent and nonadherent fractions. Both the rye antigen-adherent and nonadherent fractions proliferated similarly when they were stimulated by an unrelated antigen, Candida albicans. The rye antigen-stimulated proliferative response of rye antigen-nonadherent cells could be suppressed by coculturing with rye antigen-adherent cells from patients receiving immunotherapy. Furthermore, the treatment of cocultures with monoclonal antibody against suppressor-cytotoxic T cell (OKT8) subpopulation and guinea pig serum complement reversed the suppression. In patients receiving no immunotherapy, there was no difference in the rye grass antigen-stimulated proliferative response between the rye antigen-adherent and nonadherent fractions. These results suggest that immunotherapy induces a subpopulation of T cells that are adherent to antigen-coated plates and are capable of suppressing T cell proliferation stimulated by the specific antigen.

Detection of blocking antibodies after hyposensitization

We have studied two techniques and developed another to detect blocking antibodies in allergic asthmatic children who have been exposed to seven months of hyposensitization to house dust. These techniques were: RAST Neutralization test (RAST-N), RAST Interference test (RAST-I) and RAST Previous Adsorption test (RAST-PA). We have also determined the specific IgE values, by radioallergosorbent test (RAST), before and after the treatment and have not found a significant decrease in these levels. The percentages of positive development of blocking antibodies obtained were: 28% by RAST-N, 80% by RAST-I and 28% by RAST-PA. Thus, RAST Interference test seems to be more sensitive concerning the qualitative determination of blocking antibodies.

Chronic rhinitis

The author provides a well-detailed update on chronic rhinitis, the most common disease of the respiratory tract. Discussed are the anatomy and physiology of the nose, investigation of the patient, etiology, and treatment, including avoidance of provoking factors, pharmacologic therapy, and immunotherapy.

Increased leucocyte histamine release by Entamoeba histolytica antigen in patients with amoebic abscess of the liver

Leucocytes (basophils) from non-atopic adult subjects living in an area highly endemic with Entamoeba histolytica release histamine in a dose-dependent fashion upon in vitro exposure to an antigen of axenically grown E. histolytica (histolyticin). Leucocytes of patients with acute amoebic liver abscess were significantly more sensitive to this antigen than leucocytes of control subjects, including patients that had recovered from amoebic liver abscess. By comparison Concanavalin-A induced histamine release found in patients with amoebic liver abscess and healthy controls suggest an immunological mechanism for histolyticin induced in vitro histamine release. This is also suggested by the inability of histolyticin to release histamine from leucocytes of healthy newborn infants and the significant fall in sensitivity to histolyticin following incubation of leucocytes in acid pH. Histamine and other mediators may contribute locally to the early intense inflammatory reaction observed in tissue invasion by E. histolytica.

Dose response of IgE and IgG antibodies during ragweed immunotherapy

We studied the detailed dose-response relationship for ragweed (RW) antibody responses in 51 patients who received maximal-dose immunotherapy with crude RW extract. Serum RW-IgG and RW-IgE levels were determined by solid-phase radioimmunoassay at frequent intervals during initiation and maintenance of immunotherapy. Pretreatment RW-IgE ranged from 0.94 to 974 ng/ml (median 105); 45/51 patients had insignificant levels (less than 250 ng/ml) of RW-IgG. The maximal doses given ranged from 0.19 to 93.5 micrograms of RW antigen E per injection. All patients produced a significant IgG response (median peak 3462 ng/ml, range 689 to 24,395), and 46/51 had significant increases in IgE antibody (median peak 231 ng/ml, range 12 to 1528). A threshold dose was defined for each patient's IgG and IgE response as that dose level which initiated a persistent increment in immunoglobulin to greater than or equal to 25% of pretreatment levels. The median threshold dose for IgE was 0.13 micrograms of antigen E, which was achieved in a median time of 42 days. The threshold dose for IgG was significantly higher (median 0.56 micrograms of antigen E; p = 0.001) and occurred significantly later (median 79 days; p = 0.003). Despite variability over 3 orders of magnitude, the thresholds for IgE and IgG responses were significantly correlated for individual patients (r = 0.487; p = 0.002). The maximum RW-IgE response occurred in a median of 107 days, after which IgE antibodies declined in 46 of 49 patients. The maximal IgG response occurred significantly later (median 245 days; p less than 0.001) and then plateaued or declined modestly. The doses required to achieve maximal IgE and IgG responses were significantly correlated (r = 0.638; p less than 0.001). The maximum IgG response was positively correlated with the maximal dose of RW antigen E received (r = 0592; p less than 0.001). In 28 of the 51 patients, the incremental rise in total serum IgE was more than twice that observed for RW-IgE at the time of the maximum response, suggesting a nonspecific effect of RW immunotherapy on total serum IgE levels. This discrepancy could not be accounted for by environmental stimulation from other known allergens, as assessed by skin testing, or by pretreatment levels of RW-IgE or total IgE. These observations indicate that the human IgE antibody response during high-dose RW immunotherapy is more sensitive to both stimulation and suppression by continuous allergen administration than is the IgG response.(ABSTRACT TRUNCATED AT 400 WORDS)

Side effects during immunotherapy with purified grass pollen extracts

In a 3-year prospective double blind study, grass pollen allergic patients were allocated to perennial hyposensitization with the timothy major allergens Nos. 19 and 25 (2-component extract) or a 20-component timothy extract. The extracts were biologically standardized and adsorbed to aluminium hydroxide for treatment. Systemic side effects (SSE) had début after 1 1/2-5 h and lasted without treatment 1/2-10 h. Treatment with the 2-component extract showed preponderance of minor SSE (arthralgia, rhinitis, tiredness, headache, conjunctivitis, nausea, flu-like symptoms), but major SSE (urticaria, angioedema, asthma) were equally distributed between treatment with the two timothy extracts. Major SSE complicated the treatment before the first grass pollen season in 33% of the patients vs. only in 3% during the subsequent perennial therapy, and developed (92%) at high single dose of greater than or equal to 1,000 biological units. The majority (69%) were later able to reach the same or higher dose without relapse. Most (62%) patients with major SSE were predicted by high nasal sensitivity before treatment. Only 18% of the patients had immediate local skin reactions of greater than or equal to 2 cm, but delayed local side effects of greater than or equal to 10 cm were recorded in 70%. Immediate skin reactions did not correlate with delayed skin reactions or with SSE, but delayed local side effects tended towards negative correlation with major SSE. A mean area reduction of 50% of the delayed skin reactions was recorded by repetition of a single dose. Subcutaneous nodules appeared at single doses of greater than or equal to 5,000 biological units. Only 5% of the patients contracted nodules during initial preseasonal therapy compared with 38% during subsequent perennial dosage. The nodules contained typical benign granulomas, and the frequency in the two groups was proportionate to the quantity of aluminium in the two extracts.