重组变应原在过敏性疾病诊断和治疗中的应用

变应原特异性免疫治疗对哮喘、过敏性鼻炎有效,已广泛用于治疗Ⅰ型超敏性疾病。实验证明基于重组变应原的免疫治疗具有与天然变应原相似的效果,重组变应原被认为是免疫治疗的新型制品,有诸多的优点。基于重组变应原的免疫治疗能够改善免疫治疗临床现状,并为新的免疫治疗提供可能性。本文综述了重组尘螨变应原对哮喘和过敏性鼻炎的免疫治疗现状及进展。     

支气管哮喘特异性免疫治疗与变应原疫苗的研究进展

特异性免疫治疗(SIT)被认为是目前唯一哮喘病因治疗方法，通过基因工程技术获得纯化和标准化重组变应原能取代传统的天然变应原浸液，具有较好的免疫原性，能增强治疗的疗效。本文就近几年哮喘特异性免疫治疗与变应原疫苗研究中新进展进行回顾总结。     

支气管哮喘特异性免疫治疗与变应原疫苗的研究进展

特异性免疫治疗 (SIT)被认为是目前唯一哮喘病因治疗方法 ,通过基因工程技术获得纯化和标准化重组变应原能取代传统的天然变应原浸液 ,具有较好的免疫原性 ,能增强治疗的疗效。本文就近几年哮喘特异性免疫治疗与变应原疫苗研究中新进展进行回顾总结。     

重组变应原的基础与临床

重组变应原成为近年来变态反应研究的热点，本简要地介绍了Ｒ的重组方法和技术要点，重点探讨了变应原的Ｔ细胞和Ｂ细胞决定簇的生物学特性的差别。含有Ｔ细胞反应决定许愿重组变庆原可以封闭Ｔ细胞，使特异性ＩｇＥ的产生降低，在变态反应性疾病的治疗中具有划时代的意义。     

特异性免疫治疗的临床观察与护理

过敏性哮喘是我地区常见的变态反应性疾病之一，患者往往对多种变应原过敏，为了观察变应原的特异性免疫治疗（SIT）的疗效，收集了2004年1月～2006年10月在我院变态反应室进行各种变应原血清检测并进行SIT治疗的资料。现将其疗效及护理体会总结如下。     

呼吸道变态反应性疾病的新疗法

过敏性鼻炎和哮喘的发病率逐年上升,目前的治疗以药物控制症状为主,少部分患者接受变应原特异性免疫治疗。随着分子生物学、免疫学和遗传学等相关学科的发展,近年来已有基础和临床研究对呼吸道变态反应性疾病的新疗法进行了有益的探索,力求寻找新的靶点和途径,包括基因重组疫苗、抗IgE抗体、抗细胞因子、干预转录因子的基因表达、反义治疗和RNA干扰等,以从多方面阻断呼吸道变态反应性疾病的发生和发展。     

尘螨性变态反应疾病的免疫治疗研究进展

尘螨是一种强烈的变应原，易引起多种变态反应性疾病。目前对尘螨性变态反应性疾病的治疗仍主要采用螨体粗浸液，存在许多弊端。该文对近年来新的免疫治疗方法和疫苗的研究进展进行了综述。     

尘螨性变态反应疾病的免疫治疗研究进展

尘螨是一种强烈的变应原 ,易引起多种变态反应性疾病。目前对尘螨性变态反应性疾病的治疗仍主要采用螨体粗浸液 ,存在许多弊端。该文对近年来新的免疫治疗方法和疫苗的研究进展进行了综述。     

德国小蠊变应原Bla g2的克隆、表达及其免疫学特性鉴定

目的获得大量具有良好IgE结合活性的Bla g2重组变应原,以用于变态反应性疾病特异性诊断及免疫治疗的研究。方法提取德国小蠊总RNA,采用RT-PCR的方法扩增Bla g2片段,产物连接进入pMD18-T载体。挑取重组子,用NdeⅠ和NotⅡ双酶切后将目的片段亚克隆入pET24a(+),经IPTG诱导表达后,通过Ni2+亲和层析柱对重组变应原进行纯化,并采用Western-blot检测其免疫学结合活性。结果扩增出编码328个氨基酸的长度为984个碱基对的核苷酸片段,序列分析结果和GenBank上的基因序列(U28863)完全一致。重组变应原在E.coliBL21 star中得到高效表达,具有良好的反应原性。结论成功构建了德国小蠊变应原Bla g2的原核表达载体,并纯化出具有免疫原特性的重组蛋白,为进一步开展Bla g2蛋白和重组疫苗研究奠定了基础。     

变应性疾病特异性免疫治疗机制研究进展

特异性免疫治疗是特异性Ⅰ型变态反应性疾病的惟一有效的可以改变其自然病程的方法.虽然其机制不十分清楚,但已有很大进展.随着变应原疫苗的标准化及治疗方案的改进,使其疗效和安全性不断提高.本文综述了近几年来对特异性免疫治疗机制方面的研究进展.     

Biology of tree pollen allergens

More than 25% of the population suffer from type I allergy. Pollens from trees of the Fagales, Oleaceae, and Cupressaceae belong to the most potent and frequent allergen sources. During the past 15 years, the nature of the most important allergens has been identified by molecular biological techniques, and recombinant allergens equivalent to the natural allergens have been produced. These advances provide insight into the biological functions of important allergens and allow the development of novel forms of diagnosis and therapy. In this review, we focus on Fagales allergens to illustrate the impact of recombinant allergens on diagnosis and therapy. We discuss structural similarities as a molecular basis for crossreactivities and develop diagnostic concepts by using speciesspecific marker allergens as well as highly cross-reactive allergens. The identification of the allergen recognition profiles of patients with recombinant allergens allows a more precise selection of patients for available forms of allergy treatment. Moreover, we describe novel recombinant allergen-based forms of specific immunotherapy.     

A review of allergy and allergen specific immunotherapy

Since 20th century, when allergy was defined, an ongoing attempt for discovering the mechanisms underlying it and its treatment began. Defining allergens as well as cells such as regulatory T-cells and characterizing the antibodies involved in the pathogenesis (including blocking antibodies) have helped very much towards a better understanding of the immunologic process. However, allergen specific immunotherapy (SIT), as a specific curative treatment for allergy also dates back to the beginning of the previous century and has progressed considerably during these years. SIT similar to natural immunomodulation, directs the immune response towards tolerance. New strategies in this field, such as using recombinant allergens, T- and B-cell-epitope-containing peptides, and DNA vaccination have shown promising results. Sublingual immunotherapy, although not yet FDA-approved, as an alternative strategy in SIT has demonstrated efficacy as well as safety. Furthermore, allergen extracts, their standardization and their modification have also been the focus of much research. Undoubtedly, specific immunotherapy is proven to be an efficacious method to treat allergy, so its cost-effectiveness should be estimated in developing countries in order to include it in the country's health priorities. Informing physicians about the new anti-vaccination movement is also crucial.     

Recombinant allergens for immunotherapy.

Many of the problems associated with using natural allergenic products for allergy diagnosis and treatment can be overcome using genetically engineered recombinant allergens. Over the past 10 years, the most important allergens from mites, pollens, animal dander, insects, and foods have been cloned, sequenced, and expressed. Allergens have diverse biological functions (they may be enzymes, enzyme inhibitors, lipocalins, or structural proteins). High-level expression systems have been developed to produce recombinant allergens in bacteria, yeast, or insect cells. Recombinant allergens show comparable immunoglobulin E (IgE) antibody binding to natural allergens and show excellent reactivity on skin testing and in in vitro diagnostic tests. Recombinant allergens will enable innovative new strategies for allergen immunotherapy to be developed. These include peptide-based vaccines, engineered hypoallergens with reduced reactivity for IgE antibodies, nucleotide-conjugated vaccines that promote Th1 responses, and the possibility of developing prophylactic allergen vaccines.     

Improving pollen immunotherapy: minor allergens and panallergens

Multiple sensitizations to pollens are common clinical situations in Spain, and alter the efficacy of allergen-specific immunotherapy. We now know that optimization of the diagnosis is required to define the best suited treatment for each patient. All pollen allergens belong to 29 families of proteins - the most abundant being the expansins, prophyllins and polcalcins. The ubiquitous nature of proteins such as the prophyllins and polcalcins defines them as panallergens, and explains the cross-reactivity that is erroneously interpreted by clinicians as constituting multi-sensitization. Other families of allergens, such as the calcium transporting proteins (LTPs) are more restricted, but are associated to severe types of allergic disease - this being particularly useful to decide upon the indication of immunotherapy. Although recombinant allergens can be produced for in vitro diagnostic purposes, current legislation only allows the use of natural proteins for immunotherapy. However, the same technology can be applied to the study of extracts for vaccines, and it seems that allergen quantification by the manufacturers is a no return trip which clinicians are obliged to follow.     

Recombinant allergens/allergen standardization

Recombinant allergens are genetically engineered isoforms representing allergen molecules from allergen extracts. Immunologic responses of allergic patients toward allergen extracts define the major allergens. For the average allergic patient, the diagnostic sensitivity and treatment efficacy correlate with the concentration of major allergen. Standardization of allergen products (extracts or genetically engineered allergens) can therefore advantageously be performed using a selected recombinant major allergen as a standard. The standardization will furthermore require reagents for which both monospecific, monoclonal, or preferably, recombinant antibodies can be used. Due to differences in the allergenic activity of individual isoallergens and the naturally occurring mixture of isoallergens found in an allergen extract, and due to additional contribution to the allergenic activity from other molecules in the extract, a biologic potency assessment must always be performed as a supplement. This is also the case for a genetically engineered allergen product.     

Indications and utility of allergen provocation testing

Specific bronchial provocation tests have been used to confirm diagnosis, as a laboratory model for the study of asthma, and to evaluate the efficacy of immunotherapy with allergen extracts. However, despite the advances achieved in our knowledge of the etiopathogenic mechanisms of asthma, bronchial provocation tests with allergens have certain methodological limitations. These are due to the difficulty of evaluating these tests as regards which markers of inflammation (exhaled nitric oxide, carbon monoxide, etc.) should be investigated and at what points in the chronology of the asthmatic response. The current parameters used to assess respiratory function (FEV1, mainly) do not seem to be the most ideal nor do their percentage reductions, usually established by use, always serve to identify a bronchospastic and inflammatory response. Furthermore, the allergen doses indicated in the various protocols do not mimic natural exposure to these allergens, thus introducing an important bias in the interpretation of the results. In this sense, another and no less important difficulty is the lack of adequate standardization of the characteristics of the allergens used; the development of recombinant allergens may eliminate this obstacle and improve the reproducibility of the tests. In view of the above, the requirement of a positive bronchial provocation test to a specific allergen in the etiological diagnosis of asthma does not seem reasonable nor does it seem reasonable that specific immunotherapy is not indicated if the test is negative or that evaluation of its efficacy lies in a negative result for a previously positive test. This premise does not take into account the fact that bronchial reactivity is subject to variables that are difficult to control (prior natural exposure to the allergen, for example).     

Allergènes recombinants et immunothérapie

The development of new immunotherapy techniques using products produced by molecular biology requires that their efficacy be controlled by appropriate clinical trials. An outline of the principal molecules derived through fundamental research during the past few years will include recombinant allergens corresponding to natural allergens that are pertinent because of their high prevalence of sensitivity, hypoallergenic derivatives of recombinant allergens (polymers, fragments, molecules with mutations or amino acid deletions), hybrid molecules, T-cell epitopes, B-cell epitopes, and molecules conjugated with CpG or other co-stimulants. The biological activity of a large number of these molecules has been demonstrated in vivo. The selection of candidate molecules for immunotherapy will depend first of all on the results of preliminary open studies on a limited number of patients. Here, we report the results of five double blind immunotherapy studies, in which the control group received placebo, and in two studies another group was treated with natural extract. The most statistically significant clinical results were observed with unmodified recombinant allergens, without occurrence of severe systemic reactions. In these five studies, there was a significant increase in the level of specific IgG with the natural allergen and with the recombinant allergens. Decrease in skin test responses in the treated groups relative to the placebo group was significant in two of the three studies. Studies including a greater number of patients are now needed to meet the demands of regulatory requirements for clinical development of recombinant allergens.     

Overview of Component Resolved Diagnostics

Component-resolved diagnostics (CRD) utilize purified native or recombinant allergens to detect IgE sensitivity to individual allergen molecules and have become of growing importance in clinical investigation of IgE-mediated allergies. This overview updates current developments of CRD, including multiarray test systems. Cross-reactions between allergens of known allergen families (i.e. to Bet v 1 homologues) are emphasised. In pollinosis as well as in allergy to hymenoptera venoms or to food, CRD allows to some extent discrimination between clinically significant and irrelevant sIgE results and the establishing of sensitisation patterns with particular prognostic outcomes (i.e. sensitisations to storage proteins which correlate with clinically severe reactions in peanut allergy). Further promising improvements in diagnostics are expected from additional, not yet commercially available, recombinant allergen diagnostics identifying particular molecules of risk. Overall, CRD may decrease the need for provocation testing and may also improve the specificity of allergen-specific immunotherapy.