Latex immunotherapy: state of the art

Integrated approaches to prevent exposure risks related to latex-derived products

Natural rubber latex is a widely used industrial raw material to produce many consumer and commercial products. Chronic exposures to latex allergenic proteins residual in the finished products can promote hypersensitive immune responses, which affects millions of workers and the general public worldwide. Research has shown the average prevalence of latex allergy worldwide remains approximately 10% among healthcare workers, 7% among susceptible patients, and 4% among general population. Although most effective in preventing latex allergy, completely avoiding contact to latex-derived products is extremely challenging, given the fact that millions of products possibly contain latex, but few are regulated and properly labeled. Due to the difficulty to assure a product completely absent of latex allergens, the United States Food and Drug Administration has recommended to stop using labels like "latex-free" or "does not contain latex." Here we evaluate published data, industrial standards and regulations, identify possible countermeasures, and propose an integrated strategy, including some more practicable approaches (e.g., education/training, product labeling, the use of proper personal protective equipment, occupational selection, and searchable product database) and novel medical treatments (e.g., immunotherapy) to help decreasing latex allergy prevalence.

Latex Allergy - From Discovery to Component-resolved Diagnosis

Latex allergy is a hypersensitivity response to natural rubber latex (NRL) proteins or rubber chemicals used in the manufacture of latex products. An accurate diagnosis is the first step in the effective management of individuals with latex allergy, especially in high-risk groups, such as healthcare workers and those affected by spina bifida. Diagnosis is based on the clinical history and an accurate allergological evaluation. In the case of type I IgE-mediated hypersensitivity reactions, which can manifest urticaria, angioedema, rhinoconjunctivitis, asthma and anaphylaxis after latex exposure, skin prick tests or latex-specific IgE (sIgE) antibody detection using serological assays can be performed to confirm sensitization. Instead, in the case of contact dermatitis, a patch test can be applied to confirm the presence of a type IV T cell-mediated hypersensitivity reaction to rubber accelerators or additives. Basophils activation tests or challenge tests may be performed if there's an incongruity between the clinical history and the results of in vivo and in vitro tests. The aim of this review is to analyze the current state of the art of diagnostic techniques for latex allergy and algorithms employed in clinical practice and possible future developments in this field.

Mechanistic and Therapeutic Approaches to Occupational Exposure-Associated Allergic and Non-Allergic Asthmatic Disease

PURPOSE OF REVIEW

Occupational lung disease, including asthma, is a significant cause of disability worldwide. The dose, exposure frequency, and nature of the causal agent influence the inflammatory pathomechanisms that inform asthma disease phenotype and progression. While surveillance, systems engineering, and exposure mitigation strategies are essential preventative considerations, no targeted medical therapies are currently available to ameliorate lung injury post-exposure and prevent chronic airway disease development.

RECENT FINDINGS

This article reviews contemporary understanding of allergic and non-allergic occupational asthma mechanisms. In addition, we discuss the available therapeutic options, patient-specific susceptibility and prevention measures, and recent scientific advances in post-exposure treatment conception. The course of occupational lung disease that follows exposure is informed by individual predisposition, immunobiologic response, agent identity, overall environmental risk, and preventative workplace practices. When protective strategies fail, knowledge of underlying disease mechanisms is necessary to inform targeted therapy development to lessen occupational asthma disease severity and occurrence.

Secondary prevention of latex allergy

PURPOSE OF REVIEW

The present review addresses the secondary prevention in healthcare worker, healthcare setting, and in patients outside the healthcare setting.

RECENT FINDINGS

There is sufficient knowledge of the broad aetiology of latex allergy for secondary preventive programmes to be widely adopted. Currently, avoidance of latex-containing surgical products is mandatory in the care of sensitized patients. They should also have a list of occult sources of natural rubber latex exposure and cross-reacting fruits. During all health-care procedures latex allergic patients should be treated in a 'latex-free' environment. Specific sublingual immunotherapy has been suggested as a suitable therapeutic option. It can be offered, in addition to symptomatic treatment, to selected patients, when avoidance measures are not feasible or effective. The use of omalizumab could also be extended as an adjunct to latex immunotherapy.

SUMMARY

Despite of the progress made in the secondary prevention of latex allergy, the disease still continues to be a global health problem.

Latex Allergy: Current Status and Future Perspectives

Allergy to natural rubber latex (NRLA) from Hevea brasiliensis is a relevant public health issue, in particular in healthcare workers and groups at risk. Clinical manifestations of NRLA can range from mild skin disorders to life-threatening systemic reactions. Prevention measures remain the gold-standard treatment for patients suffering from NRLA, but the only etiological therapy able to influence the natural history of NRLA is specific desensitization. This review aims to underline the epidemiological, clinical and diagnostic aspects of NRLA, and carries out a complete and wide-ranging review of the current literature on NRLA management and immunotherapy.

The Role of Immunotherapy and Biologic Treatments in Occupational Allergic Disease

Occupational exposures are estimated to account for 15% to 25% of all adult asthma in the general population. In some cases, workplace allergen exposures can be reduced but not entirely eliminated. Given the potentially significant impact of job change, some workers may choose to continue working in a job in which there is an ongoing occupational allergen exposure. In these cases, a combined approach including personal safety measures, pharmacotherapy, and allergen immunotherapy may result in the best clinical outcomes. This review presents existing evidence for the use of immunotherapy and biologic treatments in occupational allergic disease for various occupational allergens, including wheat flour, mammalian proteins, natural rubber latex, and Hymenoptera venom. There is increasing but modest evidence on beneficial short-term and long-term effects of allergen immunotherapy and safety in worker populations. Available data suggest that allergen immunotherapy can reduce skin and respiratory symptoms and therefore allow workers to continue their current occupation.

Current insights in allergen immunotherapy

OBJECTIVE

Allergen-specific immunotherapy (AIT) in its subcutaneous and sublingual forms is currently a well-established and experimentally supported treatment for respiratory allergy and hymenoptera venom allergy. There have been advances in its use linked strictly to the advancement in the knowledge of the molecular mechanisms of allergy, the production of well-characterized extracts, and diagnostic techniques. The use of AIT in asthma and the application of new approaches are expanding. We briefly review the advances and concerns in the use of AIT.

DATA SOURCES

PubMed and Scopus.

STUDY SELECTIONS

The most recent and clinically relevant literature was selected and reviewed.

RESULTS

The introduction of high-quality products supported by large dose-finding trials has yielded better defined indications, contraindications, and modalities of use. Some specific products in tablet form have recently been approved in the United States. Sublingual immunotherapy has been found to be effective in asthma, which until recently had been a matter of debate. Another promising therapy is oral and sublingual desensitization for food allergy, for which encouraging results have recently been reported. In the near future, other options will be available, including new routes of administration (intralymphatic and epicutaneous), allergoids, engineered allergens, and peptides. The use of component-resolved diagnosis techniques will further refine and target AIT prescriptions.

CONCLUSION

This condensed and updated review shows that AIT remains a viable treatment option, especially after the introduction of standardized tablets for some allergens. Food allergy and new administration routes represent a promising expansion.

Focus on the agents most frequently responsible for perioperative anaphylaxis

Adverse reactions (ARs) to drugs administered during general anesthesia may be very severe and life-threatening, with a mortality rate ranging from 3 to 9%. The adverse reactions to drugs may be IgE and non-IgE-mediated. Neuromuscular blocking agents (NMBA) represent the first cause of perioperative reactions during general anesthesia followed by latex, antibiotics, hypnotic agents, opioids, colloids, dyes and antiseptics (chlorhexidine). All these substances (i.e. NMBA, anesthetics, antibiotics, latex devices) may cause severe systemic non-IgE-mediated reactions or fatal anaphylactic events even in the absence of any evident risk factor in the patient's anamnesis. For this reason, in order to minimize perioperative anaphylactic reactions, it is important to have rapid, specific, sensitive in vitro diagnostic tests able to confirm the clinical diagnosis of acute anaphylaxis.

Occupational Latex Allergy: the Current State of Affairs

PURPOSE OF REVIEW

Allergy to natural rubber latex (NRL) reached epidemic proportions during the nineties and led to intense preventive efforts. The aim of this review was to provide a comprehensive compilation of the current status of occupational NRL allergy.

RECENT FINDINGS

Recent advances led to the characterization of 15 NRL allergens and the development of assays for measuring the allergen content of NRL materials and specific IgE antibodies against NRL allergen components. Preventive measures aimed at reducing workplace exposure to NRL allergens were associated with decreasing incidence rates of NRL allergy. However, a pooled analysis of epidemiological surveys published during the last 10 years provided prevalence estimates of NRL sensitization and allergy similar to those derived from studies conducted before 2003. Substantial progress has been made in the understanding and prevention of NRL allergy, although the disease may still remain a worldwide cause of concern.

New developments in work-related asthma

INTRODUCTION

Work-related asthma includes two subtypes: occupational asthma or asthma caused by specific agents (sensitizers or irritants) in the workplace, and work-exacerbated asthma or pre-existing asthma worsened by workplace exposures. Areas covered: This review provides an update on the definitions and the clinical features of the different work-related asthma subtypes as well as new insights into their etiology and the pathophysiological mechanisms involved. The diagnosis of work-related asthma should be made on objective basis using a constellation of clinical, physiologic and allergologic tests. Specific inhalation challenge with the suspected occupational agent(s) remains as the reference standard for diagnosis. A literature search was performed using the following terms: work-related asthma, occupational asthma, work-exacerbated asthma, irritant-induced asthma and etiological agents. Expert commentary: Studies focusing on the biological effects and mechanisms of environmental exposures in the development of sensitizer-induced or irritant-induced asthma in various workplace settings are of greatest interest. An integrative approach that combines clinical parameters with component-resolved diagnosis as well as inflammatory biomarkers appears to be very promising. Occupational allergy provides a good opportunity to understand the complex relationships between exposure to allergens in the workplace, interaction with genes and the co-exposures to other factors in the working environment.

[Latex allergy in a paediatric hospital. Characteristics and risk factors]

INTRODUCTION

The prevalence of latex sensitisation varies according to the population studied. There are various risk factors that increase latex sensitisation, such as genetic risk, atopy, and multiple surgeries.

OBJECTIVE

To characterise patients referred to an Immunology Unit with suspected latex allergy, and to analyse their clinical features and risk factors.

PATIENTS AND METHOD

A retrospective, descriptive study was conducted on children suspected of latex allergy. Their medical records were reviewed in order to assess symptoms with contact or exposure to latex materials. Known risk factors to latex sensitisation, such as pathologies requiring repeated surgery (spina bifida, myelomeningocele, scoliosis and nephro-urological alterations), atopy (rhinitis, asthma, atopic dermatitis) were investigated. A prick test and/or specific IgE to latex were also performed. A multivariate logistic regression model was performed to find associations between symptoms triggered by exposure to latex with underlying diseases and other risk conditions.

RESULTS

A total of 106 patients were enrolled in the study, of whom 50 were evaluable. At diagnosis 96% of patients were older than five years. Most of the risk factors described were observable in these patients, such as multiple surgeries, neurological and nephro-urological malformations, surgery before one year-old, and repeated bladder catheterisation. After latex exposure, mucous cutaneous manifestations were the most common (52%), followed by respiratory symptoms (36%). All patients were sensitised and allergic to latex.

CONCLUSION

Latex allergy is a significant problem in children with risk factors. The results shown in this study raise important challenges for preventive measures and awareness.

EAACI Molecular Allergology User's Guide

The availability of allergen molecules ('components') from several protein families has advanced our understanding of immunoglobulin E (IgE)-mediated responses and enabled 'component-resolved diagnosis' (CRD). The European Academy of Allergy and Clinical Immunology (EAACI) Molecular Allergology User's Guide (MAUG) provides comprehensive information on important allergens and describes the diagnostic options using CRD. Part A of the EAACI MAUG introduces allergen molecules, families, composition of extracts, databases, and diagnostic IgE, skin, and basophil tests. Singleplex and multiplex IgE assays with components improve both sensitivity for low-abundance allergens and analytical specificity; IgE to individual allergens can yield information on clinical risks and distinguish cross-reactivity from true primary sensitization. Part B discusses the clinical and molecular aspects of IgE-mediated allergies to foods (including nuts, seeds, legumes, fruits, vegetables, cereal grains, milk, egg, meat, fish, and shellfish), inhalants (pollen, mold spores, mites, and animal dander), and Hymenoptera venom. Diagnostic algorithms and short case histories provide useful information for the clinical workup of allergic individuals targeted for CRD. Part C covers protein families containing ubiquitous, highly cross-reactive panallergens from plant (lipid transfer proteins, polcalcins, PR-10, profilins) and animal sources (lipocalins, parvalbumins, serum albumins, tropomyosins) and explains their diagnostic and clinical utility. Part D lists 100 important allergen molecules. In conclusion, IgE-mediated reactions and allergic diseases, including allergic rhinoconjunctivitis, asthma, food reactions, and insect sting reactions, are discussed from a novel molecular perspective. The EAACI MAUG documents the rapid progression of molecular allergology from basic research to its integration into clinical practice, a quantum leap in the management of allergic patients.

Allergen Immunotherapy: History and Future Developments

Allergen immunotherapy (AIT) was introduced in clinical practice more than 100 years ago. The clinical effectiveness in allergic rhinitis (and asthma) and in hymenoptera allergy was apparent early on but it was not until the mid-1900s that randomized placebo-controlled trials proved its efficacy. In the 1980s, sublingual immunotherapy (SLIT) was accepted in official guidelines. The availability of safer routes, such as SLIT, prompted increasing investigation of AIT for food allergy. The introduction of molecular-based diagnosis introduced the possibility of better targeted prescription of AIT. Other approaches are being explored, such as immunogenic peptides, recombinant allergens, and adjuvants.

Specific immunotherapy and biological treatments for occupational allergy

PURPOSE OF REVIEW

Occupational allergy represents a substantial health, social, and financial burden for the society. Its management is a complex task that, in selected cases, may also include allergen-specific immunotherapy. The purpose of this article is to review clinical data on allergen immunotherapy and biological treatments applied to occupational allergy in 2013.

RECENT FINDINGS

Immunotherapy in occupational allergic diseases has been scarcely used, and only for a few sensitizers, such as latex, flour, and Hymenoptera venom, partly due to the lack of standardized extracts. The recent use of the molecular diagnosis can improve the indication and selection of suitable allergens for preparing new standardized and powerful extracts for immunotherapy. Some recent reports suggest a beneficial role of treatment with omalizumab in workers with occupational asthma who continue to be exposed to the causal agent.

SUMMARY

Although scarce, available data suggest that immunotherapy and biological treatments may allow allergic workers to continue their work activity, but further studies are needed to standardize extracts and to evaluate the cost-effectiveness of these treatments, when exposure at the workplace cannot be avoided.

Identification and practical management of latex allergy in occupational settings

Allergy to natural rubber latex (NRL) from Hevea brasiliensis is a relevant occupational health hazard. The use of gloves and products manufactured with latex and environmental allergen exposure in the work environment are risks factors for the development of occupational allergy among different job categories. Healthcare workers have been the most commonly affected, but other professions with exposure to latex products such as hairdressers, cleaners, food handlers and those making natural rubber latex (NRL) products are also at risk of developing occupational allergy. Clinical manifestations of IgE-mediated latex allergy can range from troublesome skin disorders to life-threatening systemic reactions. It is very important to identify the occupational allergic diseases in their early stages in order to implement avoidance strategies. For this purpose, the interventions for prevention should emphasize the importance of latex allergy awareness and surveillance among exposed workforces.

Sublingual immunotherapy: recent advances

The practice of administering sublingual immunotherapy for respiratory allergy is gaining more and more diffusion worldwide as a consequence of the robust demonstration of clinical efficacy and safety provided by recent high-powered and well-designed studies, confirming for individual seasonal allergens the results of previous metanalyses in adult and pediatric populations. Preliminary evidence derives from recent rigorous trials on perennial allergens, like house dust mites, and specifically designed studies addressed the benefits on asthma. Emerging research suggests that SLIT may have a future role in other allergic conditions such as atopic dermatitis, food, latex and venom allergy. Efforts to develop a safer and more effective SLIT for inhalant allergens have led to the development of allergoids, recombinant allergens and formulations with adjuvants and substances targeting antigens to dendritic cells that possess a crucial role in initiating immune responses. The high degree of variation in the evaluation of clinical effects and immunological changes requires further studies to identify the candidate patients to SLIT and biomarkers of short and long term efficacy. Appropriate management strategies are urgently needed to overcome the barriers to SLIT compliance.

Immunotherapy in allergy and cellular tests: state of art

The basophil activation test (BAT) is an in vitro assay where the activation of basophils upon exposure to various IgE-challenging molecules is measured by flow cytometry. It is a cellular test able to investigate basophil behavior during allergy and allergy immunotherapy. A panoply of critical issues and suggestive advances have rendered this assay a promising yet puzzling tool to endeavor a full comprehension of innate immunity of allergy desensitization and manage allergen or monoclonal anti-IgE therapy. In this review a brief state of art of BAT in immunotherapy is described focusing onto the analytical issue pertaining BAT performance in allergy specific therapy.

Immunological treatments for occupational allergy

Although avoidance of occupational triggers remains the primary step in the management of work-related allergies, immunological treatments (including biological agents and specific immunotherapy) can be regarded as potential therapeutic options for IgE-mediated diseases; for example, many studies with allergen-specific immunotherapy have been carried out on latex allergy, showing overall favorable results, at least with sublingual immunotherapy. On the other hand, only few case reports have suggested the efficacy of immunotherapy in baker's asthma as well as in laboratory animal-induced asthma. The new technologies, including component-resolved diagnosis and recombinant allergens, are expected to improve the quality and efficacy of specific immunotherapy in the future. Also the use of omalizumab may represent a suitable therapeutic choice in very selected cases of occupational allergy, as well as an approach to reduce side effects of venom immunotherapy in subjects with previous severe reactions to the treatment.

Sublingual immunotherapy for allergic rhinitis and conjunctivitis

Sublingual immunotherapy (SLIT) for allergic respiratory diseases was first described in 1986 and immediately appeared as a viable alternative to the traditional subcutaneous route. Since then, more than 60 randomized controlled trials have been published, almost all with very favorable results. The average improvement over placebo in symptom score and medication use was always greater than 20%. The results of the clinical trials were pooled in several meta-analyses, which consistently confirmed the efficacy of the treatment. SLIT is characterized by a satisfactory safety profile, its side effects being mainly limited to oral discomfort. Only six anaphylaxes and no fatalities have been so far reported. Due to the good risk:benefit ratio, SLIT is currently being investigated in diseases other than respiratory allergy, such as food allergy and atopic dermatitis.