The consideration of immunotherapy in the treatment of allergic asthma

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.

Efficacy analysis of three-year subcutaneous SQ-standardized specific immunotherapy in house dust mite-allergic children with asthma

The present study aimed to evaluate the efficacy of three-year subcutaneous SQ-standardized specific immunotherapy (SCIT) in house dust mite (HDM)-allergic children with asthma. Ninety children with allergic asthma to HDMs, with or without allergic rhinitis, were randomly divided into two groups, the treatment group and the control group. The treatment group received SCIT combined with standardized glucocorticoid management and the control group received standardized glucocorticoid management alone for a period of three years. The mean daily dose of inhaled corticosteroids (ICSs), a four-week diary recording the symptom scores of asthma, peak expiratory flow (PEF) measurements, skin prick test results and serum immunoglobulin E (IgE) levels were assessed prior to treatment and following one, two and three years of treatment. The median dose of ICS was reduced in the treatment group after two and three years of treatment compared with that of the control group. After three years of treatment, the discontinuation percentage of ICS in the treatment group was higher than that in the control group. The treatment group demonstrated significantly reduced daytime and night-time asthmatic symptom scores, increased PEF values and reduced serum IgE levels after two and three years of treatment compared with those in the control group (P<0.05). In conclusion, three-year SCIT treatment combined with ICS is an effective immunotherapy for children with allergic asthma and resulted in a reduction of the required ICS dose.

Association of urinary bisphenol A concentration with allergic asthma: results from the National Health and Nutrition Examination Survey 2005-2006

OBJECTIVE

Bisphenol A (BPA) is being increasingly associated with adverse health effects. Our objective was to determine whether urinary BPA concentration is associated with allergic asthma in a representative US population.

METHODS

Data for this analysis were obtained from the National Health and Nutrition Examination Survey 2005-2006 survey and included asthma-related questions, total immunoglobulin E (IgE), 19 allergen-specific IgE levels, and urinary environmental phenol measurements. Allergic asthma was defined as a history of asthma ever, high eosinophil count, and high total IgE or atopy. Association analyses included dichotomous and polychotomous logistic regression, receiver operating characteristic curves, Akaike information criterion, and likelihood ratio χ(2).

RESULTS

We found that 10-fold increase in BPA was independently associated with a higher likelihood of allergic asthma in females [odds ratio (OR) = 2.21, p = .032] but not in males (OR = 0.83, p = .474). These findings were reaffirmed when allergic asthma was defined based on atopy rather than total IgE (OR = 2.45, p = .001 in females and OR = 0.83, p = .605 in males). Urinary BPA was significantly associated with sensitization to various specific allergens in a dose-response manner. Lastly, urinary BPA independently predicted an asthma episode in the past 12 months in females but not in males.

CONCLUSIONS

Urinary BPA is significantly associated with allergic asthma in females.

Clinico-immunological changes post-immunotherapy with Periplaneta americana

BACKGROUND

Cockroach proteins induce allergies including asthma in predisposed individuals. Well-designed controlled studies are required to show the effect of cockroach immunotherapy (IT). This study is aimed to assess changes in clinical and immunological parameters post-IT with Periplaneta americana extract.

MATERIALS AND METHODS

A double-blind, placebo-controlled trial of cockroach IT was performed for 1year in 50 patients of asthma, rhinitis or both. The efficacy of IT was assessed by change in skin reactivity and clinical parameters such as symptom/drug score, airway reactivity and immunological parameters namely IgE, IgG1 and IgG4, IL-4 and IFN-γ by enzyme-linked immunosorbent assay and western blotting using patients' sera at baseline and after 1year of treatment.

RESULTS

Immunotherapy with cockroach extract demonstrated significant improvement in clinical parameters of active group patients compared with baseline values and placebo group. Specific IgE levels showed a modest reduction, while IgG4 levels increased significantly in active IT group after 1year. IgE immunoblotting demonstrated reduction in intensity and number of specific bands, whereas IgG4 binding showed more number and distinct bands following IT. Active group patients showed correlation between increase in IgG4/IgG1 ratio and reduction in symptom score post-IT.

CONCLUSIONS

Immunotherapy with cockroach extract improved clinical and immunological status of asthma and rhinitis patients. Clinical improvement in patients after IT is associated with immunological changes.

Specific immunotherapy in asthma: efficacy and safety

The use of specific immunotherapy (SIT) to treat asthma has been, and still is, a matter of debate, and there are no clear or unequivocal indications in the official documents. This is partly due to the fact that there are few studies specifically designed to assess asthma, that none of such studies had a formal sample size calculation, and that objective parameters of pulmonary function have been assessed only sporadically. Nonetheless, there are good quality studies for both subcutaneous immunotherapy (SCIT) and sublingual immunotherapy (SLIT) where asthma symptoms were evaluated, and showing positive results. Moreover, several favourable meta-analyses are available, although their validity is limited by the great heterogeneity of the trials included. The disease modifying effect of SIT, that is the capacity of preventing asthma onset should be also taken into account. Concerning the safety, fatalities seem to be an exceptional event and in Europe no fatality has been reported over the last two decades. Uncontrolled asthma is universally recognized as the most important risk factor for severe adverse events. In conclusion both SLIT and SCIT can be used in asthma associated with rhinitis (which is the most common condition), provided that asthma is adequately controlled by pharmacotherapy. In such case, a measurable clinical benefit on asthma symptoms can be expected. On the other hand, SIT cannot be presently recommended as single therapy when asthma is the unique manifestation of respiratory allergy.

Clinical efficacy of house dust mite-specific immunotherapy in asthmatic children

BACKGROUND

Immunotherapy has been widely used in the treatment of allergic diseases. We evaluated the clinical efficacy of specific immunotherapy with extracts of Dermatophagoides pteronyssinus (Dp) and Dermatophagoides farinae (Df) in children with asthma.

METHODS

All 40 children had moderate-to-severe asthma and positive allergen tests for Dp and Df. All required daily medication. They were randomly assigned to two groups: Half of them received immunotherapy with subcutaneous injections of Dp and Df extracts, while the other half were not given immunotherapy. Participants were followed up for more than 6 months.

RESULTS

Children in both groups had apparent improvements in medication use and symptoms after 6 months. The mean medication scores declined from 3.6 +/- 1.14 to 1.7 +/- 0.66 in the immunotherapy group (p < 0.01) and from 3.35 +/- 0.87 to 2.4 +/- 1.09 in the control group (p < 0.01). There was a significant difference between the two groups (mean difference 0.95; p < 0.01). The symptom score improved in the immunotherapy group from 2.65 +/- 0.98 to 1.20 +/- 1.00 (p < 0.01) and in the control group from 2.55 +/- 0.99 to 1.40 +/- 0.88 (p < 0.01), with a significant difference between the two groups (mean difference 0.3; p < 0.01). The number of office visits in the immunotherapy group was greater than that of the controls, but the frequencies of emergency room visits and hospitalization decreased.

CONCLUSION

Our study showed that specific immunotherapy with Dp and Df was beneficial for asthmatic children.

Local and systemic reactions occurring during immunotherapy: an epidemiological evaluation and a prospective safety-monitoring study

The efficacy of specific immunotherapy in allergic patients with IgE-mediated rhino-conjunctivitis, asthma and allergic reaction for stinging insects suggests the opportunity of improving technical procedures to minimize risk and optimise the safety of immunotherapy. This study investigated both local and systemic reactions, occurring in a population of 218 patients undergoing immunotherapy, in an attempt to correlate them with some parameters as well as age, sex and allergenic extracts. The epidemiological evaluation was based on the administration of a questionnaire to 218 patients in order to assess possible reactions to immunotherapy. The following data were evaluated: personal data, diagnosis, specific allergens, adverse reactions undergone during treatment, number of reactions and symptoms. The patients were followed-up by the medical staff of the Section of Allergological and Immunological Disease (SAID), University of Bari (Bari-Italy) for compilation of questionnaires. We found a correlation between female sex and adverse reactions. Among 107 patients referring reactions to the immunotherapy, 71 patients (66.3%) presented only local reactions; 11 patients (10.3%) systemic reactions and 25 patients (23.4%) systemic reactions associated with local reactions. Parietaria was mostly involved in patients with local reactions, instead, in patients with systemic reactions the prevalent allergens seem to be Dermatophagoides and grass-pollen. Rhinitis was the most frequent diagnosis for patients who have presented both local and systemic reactions. In our study, we had frequently mild systemic reactions and some cases of respiratory difficulties, while it is evident that in our group of patients no cases of anaphylaxis occurred. In addition, we considered some events before the administration of immunotherapy, such as assumption of drugs, meals, exposure to sun, stress or physical activity and the percentage of adverse reactions. On the light of a small number of fatality, immunotherapy represents a safer therapy for allergic diseases; nevertheless, our data suggest that safety is strictly correlated with prescriptions by specialists, administration by trained physicians and accurate follow-up of patients. In particular it is recommended to avoid some events before the administration of immunotherapy, above all the assumption of drugs and physical exercise.

Long-term allergen-specific immunotherapy correlates with long-term allergen-specific immunological tolerance

INTRODUCTION

One method of treatment for allergic diseases is allergen-specific immunotherapy (SIT). The clinical efficacy of SIT in pollen-induced allergic rhinitis has been demonstrated in several controlled clinical trials. There is no consensus about the protective effect of SIT. In this study, we evaluated the correlation between the duration of SIT and relapse of allergic rhinoconjunctivitis.

METHODS

We evaluated 148 patients who had received SIT between 1998 and 2006. All of the patients had allergic rhinoconjunctivitis. According to the data 116 had sensitivity to grass pollen and 32 to house dust. SIT was performed on 87 patients for 4 y (Group A) and 61 patients for 6 y (Group B).

RESULTS

All of the 148 patients were monitored regularly with no medication for 2 y after SIT. Thirty-one patients in Group A relapsed (36%); 11 patients in Group B relapsed (18%). Mean duration until relapse was 11.1+/-1.99 mo in Group A and 19.64+/-1.86 mo in Group B. During evaluation, symptom scores were 2.32+/-0.74 in Group A and 1.81+/-0.75 in Group B and serum total immunoglobulin E levels were 432.4+/-78.5 KU/lt in Group A and 288.6+/-55.3 KU/lt in Group B. There was significant difference between the groups (P < 0.05).

CONCLUSION

According to these results, long-term SIT therapy correlates with long-term, allergen-specific, acquired immunological tolerance.

Quality of care in patients with asthma and rhinitis treated by respiratory specialists and primary care physicians: a 3-year randomized and prospective follow-up study

BACKGROUND

Previous studies evaluating asthma care provided by primary care providers and respiratory specialists (RSs) are limited by short observation periods and nonrandomized designs.

OBJECTIVE

To evaluate long-term outcomes in patients with asthma and rhinitis randomly selected to be cared for by RSs or primary care specialists.

METHODS

In a randomized, 3-year, longitudinal study, 472 patients with asthma and allergic rhinitis were cared for by RSs or primary care physicians. Outcome measures, including disease severity, lung function, medication use, compliance, and self-management knowledge, were compared between groups.

RESULTS

Compared with patients followed up by primary care providers, those in the RS group had reduced asthma severity (P = .046), significantly fewer days with asthma symptoms (P < .01), and improved asthma self-management knowledge (P < .01). At baseline, most patients were undertreated. This value was significantly reduced from 74% to 37% in the RS group and from 71% to 57% in the primary care physician group. We found odds ratios of 8.5 (95% confidence interval, 2-43; P < .01) for worsening of asthma and 0.3 (95% confidence interval, 0.1-0.9; P = .04) for asthma improvement when followed up by primary care physicians, which indicates that primary care follow-up increases the risk of worsening of asthma and decreases the chance of improving. Similar results were observed in patients with allergic rhinitis, although the findings were less pronounced.

CONCLUSION

Treatment and follow-up by an RS ensured better quality of care in patients with asthma and rhinitis.

Protective efficiency of dendrosomes as novel nano-sized adjuvants for DNA vaccination against birch pollen allergy

We evaluated the use of a novel gene porter (Den123--a nontoxic self-assembled dendritic spheroidal nanoparticle made of biodegradable monomers), aiming to enhance and improve the desired immune response in protection from allergy. Footpad DNA immunization in Balb/c mice was done three times using the Bet v 1a gene with or without Den123 with 2-week intervals followed by sensitization with rBetv1 (5 microg) in alum twice in a weekly interval. Different doses of pCMV-Betv1 were used (10 microg and 100 microg). The protective role of different formulations was evaluated by measuring the IgG1, IgG2a and IgE antibody production, cytokine release of isolated splenocytes and beta-hexosaminidase release from the RBL cells. Higher and increasing ratios of IgG2a/IgG1 were seen in mice which received plasmids in combination with Den123. Den123 and DNA vaccine synergistically enhanced the Interferon gamma released from splenocytes. In the presence of Den123, IgE inhibition was independent of the dose and type of the injected DNA. All DNA-pre-immunized mice demonstrated low basophil degranulation. It is therefore concluded that administration of the DNA entrapped in Den123 nanoparticles results in sustained release of plasmids, Th1/Th2 balanced immune response with promising IgE inhibition. Also higher amounts of DNA contributed to stronger Th1 response.

The Safety of Immunotherapy in Patients with Allergic Asthma and Allergic Rhinitis

We studied systemic reactions associated with immunotherapy in a group of 50 patients with mean age 31.4 years. The group consisted of 36 women and 14 men who followed a three-year immunotherapy treatment with pollen and mite allergen extracts (HAL-Holland Corporation). A total number of 2550 injections were administered. Eight patients developed systemic reactions; 6 had allergic rhinitis and 2 allergic asthma. None developed severe anaphylaxis. Seven of the systemic reactions occurred immediately after injection while one was a late reaction manifested as generalized urticaria, local edema and rubor at the site of the injection. From the 7 patients who showed an immediate reaction, 5 developed generalized urticaria with local edema and rubor at the site of the injection, while 2 presented with bronchial spasm. We did not observe any reaction when the quantity of the extract injection was reduced by 50%. Our study points out that, in the vast majority of cases, immunotherapy is free of severe systemic reactions. Those that occur are associated with the injection of high-density extracts and none of them is severe.

New approaches in immunotherapy: allergen vaccination with immunostimulatory DNA

Despite its success, conventional immunotherapy is saddled with a number of encumbrances. An allergenic vaccine that could reduce allergenicity, maintain immunogenicity, and be given in a few doses would have important therapeutic implications, as millions of patients with poorly controlled allergic rhinitis and asthma would be candidates for such a form of immunomodulation. This article addresses a specific adjuvant approach to immunotherapy in which highly active immunostimulatory phosphorothioate oligodeoxyribonucleotide moieties are linked to the principal allergenic moiety of a relevant aeroallergen.

Antigen-immunostimulatory oligonucleotide conjugates: mechanisms and applications

Conjugation of protein antigen with immunostimulatory oligonucleotides creates a potent immunogen. Physical linking of oligonucleotides to antigen enhances antigen uptake and targets the adjuvant properties of the oligonucleotides to the antigen-presenting cell. In addition, the conjugated oligonucleotides appear to have improved immunostimulatory abilities compared to free oligonucleotides, presumably due to enhanced activation of Toll-like receptor 9. Immunization with these conjugate preparations elicits antigen-specific antibody responses, a T-helper cell 1-biased cytokine profile from CD4 T cells, and CD8 cytotoxic T-lymphocyte activity that is CD4 independent. The humoral and cellular immune responses induced by these conjugates suggest they can be used to create effective vaccines against infectious pathogens and tumors and to beneficially modulate allergic responses. Indeed, recent clinical trial data show symptom relief and immunomodulation of the allergic response in patients with allergic rhinitis. This review considers the mechanisms of action of antigen-oligonucleotide conjugates and discusses available data regarding their use for the prevention and treatment of infectious, oncologic, and allergic diseases.

Clinical practice guidelines and specific antigen immunotherapy

Allergy immunotherapy is a safe, effective treatment modality in selected patients. The length of therapy and the wide variety of patient sensitivities make it difficult to develop and test evidence-based guidelines in all areas of immunotherapy. A review of techniques and the evidence supporting them is provided in this article.

Impaired secretion of interleukin-4 and interleukin-13 by allergen-specific T cells correlates with defective nuclear expression of NF-AT2 and jun B: relevance to immunotherapy

BACKGROUND

Allergen immunotherapy (IT) is a successful treatment associated with decreased Th2 cytokine production by allergen-specific T cells. We have previously demonstrated (Faith et al., J Immunol 1997; 159:53-57) that inhibition of Th2 cytokine production in vitro correlates with impaired tyrosine kinase activity through the TCR. The transcription factor complex, nuclear factor of activated T cells (NF-AT), which regulates Th2 cytokine production is controlled by the activity of tyrosine kinases.

OBJECTIVE

To address whether decreased Th2 cytokine production by allergen-specific CD4+ T cells following IT is correlated with altered translocation and nuclear expression of the NF-AT family member, NF-AT2, and the activator protein 1 (AP1) component of NF-AT, jun B.

METHODS

T cell lines specific for insect venom phospholipase A2 (PLA) were derived from patients prior to and during conventional venom IT. Nuclear expressions of NF-AT and jun B were assessed following stimulation through the TCR. Th1 and Th2 cytokine and IL-10 production by insect venom-specific T cells were also determined. Results were compared with a well-established model system in which anergy was induced in cloned, allergen-specific Th2 cells.

RESULTS

Impaired translocation and decreased expression of NF-AT2 and jun B were detected in PLA-specific T cell lines derived from bee venom-allergic individuals following 16 weeks treatment compared to pre-treatment. These results correlated with significantly reduced production of IL-4 and IL-13 and significantly increased production of IFN-gamma and IL-10 by PLA-specific T cells. Impaired IL-4 and IL-13 production also correlated with defective nuclear expression of NF-AT2/jun B in cloned, anergic allergen-specific Th2 cells.

CONCLUSION

These results suggested that optimal production of IL-4 and IL-13 by allergen-specific T cells is dependent on the nuclear expression of NF-AT2 and jun B. Thus, specific inhibition of NF-AT2/jun B might be an option in novel and improved forms of allergen IT.

The Effects of Long-Term Treatment by Immunotherapy and Fluticazone on Broncial Hyperreactivity

Thirty subjects (20 female and 10 male), all allergic to the mites D. Pteronyssinus and D. Farinae, participated in the present study which covered a period of four years. The subjects were randomly divided in two groups. Group I included 10 female and 5 male subjects, with an average age of 25.8 (+/− 3.5) years who received immunotherapy only. Group II had an average age of 31.5 (+/− 4) years and they received immunotherapy along with fluticazone propionate (1000mcg/day). The protocol for immunotherapy was the same for both groups. The basis FEV1 was determined for each subject of both Groups I and II and afterwards they were subjected to provocation tests of nebulized methacholine solution administered in consecutively larger concentrations until a drop in FEV1 >20 % (PC20), was observed. Three years later, when their therapy was completed, all subjects were subjected to the same provocation test and a significant reduction in bronchial hyperactivity was documented for both groups. In particular, for Group I, the percentage of change in FEV1 values was 27.25 +/- 5.23 % and PC20 5.11 +/− 2.64 mg/ml before immunotherapy, while after immunotherapy the same indicators were 22.22 +/- 7.08 % (P<0.05) and 6.85 +/− 4.03 mg/ml, (P<0.05) respectively. For Group II, the percentage of change in FEV1 values was 26.28 +/− 2.5 % and PC20 5.42 +/− 2.5 mg/ml before immunotherapy, while after immunotherapy the same indicators were 12.27 +/- 2.49 % (P<0.01)and 11.64 +/− 5.14 mg/ml, P<0.01 respectively. It is concluded that although significant reduction in hyperreactivity can be achieved through immunotherapy, the combination of immunotherapy with daily fluticazone propionate administration shows the most promising results.

Molecular aspects of allergy

Atopic diseases such as asthma, rhinitis, eczema and food allergies have increased in most industrialised countries of the world during the last 20 years. The reasons for this increase are not known and different hypotheses have been assessed including increased exposure to sensitising allergens or decreased stimulation of the immune system during critical periods of development. In allergic diseases there is a polarisation of the Th2 response and an increase in the production of type 2 cytokines which are involved in the production of immunoglobulin E and the development of mast cells, basophils and eosinophils leading to inflammation and disease. The effector phase of atopy is initiated by interaction with Fc epsilon RI expressed on effector cells such as mast cells and basophils but also found on an ever increasing list of cells. Binding of a polyvalent allergen to the variable part of IgE leads to a cross-link of the receptor that triggers the cell to release histamine and pharmacological mediators of the symptomatic allergic response. Cross-linking of Fc epsilon RI by autoantibodies against the alpha-chain of the Fc epsilon RI, causing subsequent histamine release is thought to be involved in the pathogenesis of other diseases such as chronic idiopathic urticaria (CIU). To date, most therapeutic strategies are aimed at inhibiting and controlling components of the inflammatory response. Recently, new treatment strategies have emerged that focus on the development of preventive and even curative treatments. The most promising therapeutic approaches are aimed at inhibiting the IgE-Fc epsilon RI interaction with the use of non-anaphylactogenic anti-IgE or anti-Fc epsilon RIalpha autoantibodies. Clinical trials in humans using an humanised anti-IgE antibody showed that this antibody was well tolerated and reduced both symptoms and use of medication in asthma and allergic rhinitis. Thus interruption of the atopic cascade at the level of the IgE-Fc epsilon RI interaction with the use of non-anaphylactogenic antibodies is effective and represents an attractive therapy for the treatment of atopic disease.

Immunotherapy for allergic asthma

Specific allergen immunotherapy is an effective treatment of allergic asthma. Double-blind studies provide proof of benefit, although seasonal or intermittent asthma consistently responds better than perennial asthma. Advantages of immunotherapy compared with most pharmacotherapies include modification of the natural history of allergic disease, reduction of need for chronic medication, and treatment of both upper and lower airway disease simultaneously. Improvements in immunotherapy occurred in the later portion of the twentieth century because of enhanced understanding of immunotherapy's mechanism of action, recognition of the dose effect, and improved quality and consistency of allergen vaccines. Purified inhibitors of specific mediators of the allergic response, products of biotechnology, will probably lead to improvements of immunotherapy of asthma in the twenty-first century. The future of immunotherapy and other immunomodulation of allergic asthma is promising.

Can knowledge of the molecular structure of allergens improve immunotherapy?

Conventional immunotherapy may be associated with the development of adverse reactions, including anaphylaxis, due to the use of increasing doses of allergen. Standardization of extracts is necessary in order to assess the correct amount of allergen administered. In recent years, increased knowledge on the molecular structure of allergens has allowed the development of novel alternatives for immunotherapy. Initially, allergens were cloned and expressed as recombinant proteins in eukaryotic and prokaryotic systems. Crystallization of the purified proteins led to the elucidation of the tertiary structure of the allergen. Molecular biology techniques were used to construct modified allergens whose new IgE binding properties were studied. IgE antibody mapping combined with molecular modeling has allowed the recognition of IgE binding sites on the surface of the molecule. This information has been applied to the engineering of new modified allergens, with and without adjuvants, that retain immunogenicity but with reduced allergenicity. The use of these molecules for immunotherapy should allow the administration of greater doses of allergen, without the undesired side effects characteristic of conventional immunotherapy.

TH2 lymphocytes from atopic patients treated with immunotherapy undergo rapid apoptosis after culture with specific allergens

BACKGROUND

In atopic patients treatment with specific immunotherapy (SIT) induced a shift in the balance of T-cell immune response away from a T(H)2-type (producing mostly IL-4) in favor of a T(H)1-type T-lymphocyte response (with the preferential production of IFN-gamma). However, the mechanisms through which SIT acts are less clear. We have recently shown that allergens may induce an activation-induced cell death process in lymphocytes from SIT-treated atopic patients.

OBJECTIVE

This study aimed to determine whether allergen-induced apoptosis can occur in a specific subset of cells.

METHODS

The study was performed in lymphocytes from normal subjects and atopic patients, some of whom were treated with SIT. Cells were cultured in the presence of gramineous pollen (Lolium perenne) allergenic extracts. Cell phenotype and intracellular cytokine expression were measured by means of fluorescent mAbs. Apoptosis was measured by using terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick end-labeling. Fluorescence was analyzed in a FACScan flow cytometer, and the data were evaluated with Consort 30 software.

RESULTS

Our results showed that allergens induce apoptosis of lymphocytes in SIT-treated atopic patients. Apoptosis occurs mainly in T(H)2 lymphocytes with the IL-4+/CD4+ phenotype and subsequently increases the percentage of IFN-gamma(+) cells in the culture.

CONCLUSION

These results suggest that the shift from T(H)2 to T(H)1 induced by SIT in atopic patients may be mediated, at least in part, by the induction of an activation-induced cell death process in allergen-responder T(H)2 cells.

Cockroach allergens and asthma

Asthma and allergy are the most common diseases associated with cockroach infestation of houses in the United States and other parts of the world. Sensitization and exposure to cockroach allergens is associated with increased asthma morbidity in the United States, especially among lower socioeconomic groups, including African American and Hispanic populations. Exposure to cockroach allergens in the first 3 months of life has been associated with repeated wheezing and asthma. The principal domestic cockroach species are Blattella germanica and Periplaneta americana. Both species produce several potent allergens, including Bla g 2 (inactive aspartic proteinase), Bla g 4 (calycin), Bla g 5 (glutathione-S-transferase), the group 1 cross-reactive allergens Bla g 1 and Per a 1, and tropomyosin. Structural homology between tropomyosins from cockroaches, mites, and shrimp may explain clinical cases of the oral allergy syndrome. The 3-dimensional structures of several cockroach allergens are known, and biologically active recombinant allergens have been produced in high-level expression vectors. The use of recombinant cockroach allergens should allow mechanisms of cockroach-induced asthma to be investigated and may lead to the development of new approaches to asthma treatment. Environmental allergen measurements of Bla g 1 and Bla g 2 have allowed exposure levels that cause allergic sensitization to be established. Abatement studies have shown that a sustained decrease in cockroach allergen levels is difficult but can be accomplished by professional application of insecticides, together with rigorous household cleaning. Cockroach asthma is an important public health problem that affects patients who are the least likely to be compliant with treatment with asthma medications or environmental control. Patient education, improvements in the housing stock, and improvements in environmental and immunologic treatment strategies are likely to be the most successful approaches to reduce the prevalence of cockroach-induced asthma.

New trends in immunotherapy to prevent atopic diseases

Advances in the understanding of the molecular and cellular immunological mechanism of atopy have led to the development of new therapies for allergic diseases. However, only a few new drugs have reached the clinic and none provides long-term immunomodulatory effects. Immunotherapy, through its capacity to produce a long-term, antigen-specific, protective immune response, is the only aetiologic treatment that offers the possibility of preventing or even curing atopic diseases. However, the potential severe side-effects associated with conventional immunotherapy using whole allergen extract limits its widespread use. Thus, novel strategies to minimize the side-effects and improve the efficacy of immunotherapy are of considerable interest in the treatment of atopic diseases. Promising animal and human studies, using approaches such as peptide immunotherapy, DNA vaccination, CpG oligonucleotides and mycobacterial vaccines, suggest that it might be possible to prevent or cure atopic diseases in the future.

The role of cockroach allergens in asthma

Cockroach allergy has been recognized as an important cause of asthma. Cockroach asthma has been described as a more severe disease, associated with perennial symptoms and high levels of total IgE. Cockroaches produce several allergens that induce sensitization, and exposure to high levels of cockroach allergens in the home is a major risk factor for symptoms in sensitized individuals. Previously identified allergens from Blattella germanica and Periplaneta americana, the most important domiciliary species, include Bla g 2 (inactive aspartic protease), Bla g 4 (calycin), Bla g 5 (glutathione-S-transferase), Bla g 6 (troponin), the Group 1 cross-reactive allergens Bla g 1 and Per a 1, Per a 3 (arylphorin), and Per a 7 (tropomyosin). Strategies for decreasing environmental exposure to cockroach have been recently investigated. The results suggest that a sustained decrease in cockroach allergen levels is difficult to accomplish, even after successful extermination of cockroach populations. Cockroach allergens have been cloned and produced as recombinant proteins in high-level expression vectors. The use of recombinant cockroach allergens should allow mechanisms of cockroach-induced asthma to be investigated and may lead to the development of new approaches to asthma treatment in the future.

Effect of allergist intervention on patient-centered and societal outcomes: allergists as leaders, innovators, and educators

Atopic disorders, which afflict millions of Americans and hundreds of millions worldwide, are at epidemic levels with concomitant increases in morbidity and mortality. Environmental and lifestyle changes over the past three to five decades are proposed causes for this pandemic and as such present major burdens to reverse. The scope of allergy practice bridges directly on this challenge. Allergy as a specialty is a major leader in developing effective strategies to confront this epidemic. Allergists have made major contributions to the understanding of the risk factors, immunology, pathophysiology, immunomodulation, and prevention of atopic and immunologic disorders. Allergist epidemiologists and clinicians have helped develop and implement national and international guidelines in the recognition, management, and prevention of asthma and rhinitis. Allergist clinical researchers are active in (1) outcomes research that demonstrates convincingly the value of allergy as a specialty in asthma, allergic rhinitis, anaphylaxis, drug and food allergy, and other atopic disorders, (2) National Institutes of Health clinical trials that will form the basis for the future treatment of asthma and allergic disease, and (3) pharmaceutical trials that evaluate new, effective, and safe medication to treat atopic disease. Allergist educators, comprising academic and practicing allergists, supported by allied health professionals, national associations, and affiliated lay organizations, provide comprehensive education to fellows, residents, colleague physicians, media, the public, and patients. Documentation of the value of allergists in improving patient-centered and societal outcomes in their core domain, allergy, is the appropriate final topic contribution in the important series "New millennium: The conquest of allergy."

Prevention of asthma morbidity: recent advances

Asthma prevalence has risen substantially in recent decades and is an increasing cause of disability for American children. Concern about the rise in morbidity has led to treatment guidelines and a growing body of clinical research. Recent trials continue to support the role of inhaled corticosteroids as the most effective therapy to control airway inflammation associated with persistent asthma. Growth suppression due to inhaled corticosteroids has also been well documented, although the long-term effects and relative potencies of different agents require further study. Other anti-inflammatory agents such as cromolyn and the new class of leukotriene receptor antagonists have demonstrated benefit in milder patients. Leukotriene receptor antagonists and long-acting beta2-agonists may allow for reduction of inhaled steroid doses. Control of environmental allergens and irritants is essential. New evidence suggests an increasingly important role for allergen immunotherapy.