Patterns of latex allergen recognition in children sensitized to natural rubber latex

Latex allergy guidelines for people with spina bifida

An estimated 85% of individuals with spina bifida (SB) survive into adulthood, warranting SB-specific transition to adult healthcare guidelines to address the diverse and complex medical, adaptive, and social needs particular to this condition. Latex allergy constitutes one important health concern for this population that requires ongoing and life-long evidence-based management. This article discusses management of latex allergy according to the SB Latex Allergy Healthcare Guidelines from the 2018 Spina Bifida Association's Fourth Edition of the Guidelines for the Care of People with Spina Bifida, reviews current care models in which such latex allergy guidelines can be implemented, and explores further relevant research topics in SB care relative to latex allergy.

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.

Low prevalence of latex allergy in children with spinal dysraphism in non-latex-free environment

BACKGROUND

Studies in the past have shown that children with spinal dysraphism have highly prevalent latex allergy. These children have a spectrum of congenital spinal anomalies, caused by defects in neural tube closure, with an incidence of 1 in 1000 births. Proposed risk factors for latex allergy include multiple surgeries since birth, including an insertion of a ventriculoperitoneal shunt, elevated IgE titers, repeat multiple catheterizations, and atopy. In the 1990 s, studies published in the United States and Europe showed a latex allergy prevalence of over 70% in these patients. On the other hand, studies published years later in other countries showed a declining prevalence of no more than 17%.

OBJECTIVE

Our goal was to prospectively assess the prevalence of latex allergy in children with spinal dysraphism in our non-latex free environment center compared with a control group.

STUDY DESIGN

The study group included 58 children with spinal dysraphism attending our center between 2010 and 2013. Findings were compared to 65 children referred for evaluation of allergic diseases. The parents completed questionnaires assessing personal and familial history of allergic diseases. All children were tested for blood latex IgE-specific antibodies (IMMULITE 2000).

RESULTS

The mean age was 120.9 (67.6) months in the study group and 129.5 (68.5) months in the control group (p = 0.27). The corresponding median number of surgical procedures was 2 (range 0-10) and 0 (range 0-4), and mean duration of clean intermittent catheterization was 52 (72.2) months in the study group. Positive IgE antibodies and clinical allergic reactions were low with very similar prevalence in both groups (Figure).

DISCUSSION

Our results show considerable lower latex allergy and sensitization than studies published in the United States and Europe in the past, despite the fact that our center utilizes minimal avoidance measures for latex allergy. Study limitations include the relatively small number of patients in our single-center study. Moreover, our control group could not include normal volunteering healthy children due to institutional review board refusal.

CONCLUSIONS

Children with spinal dysraphism in our center have a low prevalence of latex allergy. Possible explanations include low latex protein content gloves and catheters used worldwide, including our center, lower number of surgeries, or a disease associated propensity for latex sensitization with a geographically variable genetic association. More studies are needed to validate our conclusion that using minimal avoidance measures, without maintaining a strict latex free environment, seems sufficient to prevent clinical latex allergy, at least in the Mediterranean region.

Molecular allergy diagnosis: status anno 2015

IgE antibodies play a key role in type I allergic reactions. Today, different in vitro immunoassays for allergen-specific IgE antibodies are available. However, some major issues should be taken into account for correct interpretation of specific IgE (sIgE) antibody results, as these assays do not demonstrate absolute positive and negative predictive values. Therefore, additional diagnostic tests are needed to make the correct diagnosis. During the last two decades significant progress in biochemistry and molecular biology enabled the detection and quantification of sIgE antibodies to allergen protein components and epitope-emulating peptides, also called molecular allergy diagnosis or component resolved diagnosis (CRD). In contrast to conventional sIgE antibody assays, molecular allergy diagnosis makes it possible to discriminate between genuine allergy and merely sensitisation, to establish personalized sensitization patterns and to assess the individual risk of severity of an allergic reaction and finally it helps us to predict the natural course. In this review the use of CRD in inhalant, food, latex and hymenoptera venom allergy will be discussed. The primary focus will be on the most relevant clinical applications of CRD rather than to describe all the currently available allergen components and epitopes. Appropriate experience of our own research group is provided.

Microarray-based component-resolved diagnosis of latex allergy: isolated IgE-mediated sensitization to latexprofilin Hev b8 may act as confounder

Immediate type allergy to latex is still a widespread problem. Latex-allergic patients undergoing diagnostic and operative medical procedures are at risk of potentially life-threatening reactions. Accurate diagnostic methods are therefore crucial. The aim of this retrospective study was to discriminate between sensitization and relevant allergy to latex based on an easy and suitable diagnostic approach. In 14 patients with clinical symptoms and 27 controls, latex skin prick tests (SPT), IgE against latex (CAP) and serological component resolved specific latex-allergen determination (Hev b1, b3, b5, b6, b7, b8, b9, b10, b11) based on ImmunoCAP ISAC were performed. SPT correlated very well with clinically manifest latex-allergy demonstrating a high specificity (95%) (and a low sensitivity). However, CAP levels to crude latex could not safely discriminate between purely sensitized and latex-allergic patients. The majority of patients mono-sensitized to the latex profilin Hev b8 did not suffer from any relevant symptoms upon contact with latex. However, in two patients with latex-allergy diagnosed by elevated specific IgE only sensitized against Hev b8, additional sensitization to carbohydrate cross-reactive determinants (CCD) was found. In the case of positive serum IgE against latex and negative SPT, component-resolved diagnosis including IgE against specific latex-proteins, specially Hev b8, and carbohydrate cross-reactive determinants (CCD) is a useful tool to discriminate between latex-sensitization and latex-allergy.

Molecular diagnosis in allergy

Development and progress made in the field of recombinant allergens have allowed for the development of a new concept in allergy diagnosis, molecular diagnosis (MD), which makes it possible to identify potential disease-eliciting molecules. Microarray-based testing performed with a small amount of serum sample enables clinicians to determine specific-IgE antibodies against multiple recombinants or purified natural allergen components. Performance characteristics of allergens so far tested are comparable with current diagnostic tests, but have to be confirmed in larger studies. The use of allergen components and the successful interpretation of test results in the clinic require some degree of knowledge about the basis of allergen components and their clinical implications. Allergen components can be classified by protein families based on their function and structure. This review provides a brief overview of basic information on allergen components, recombinants or purified, currently available or soon to become commercially available in ImmunoCAP or ISAC systems, including names, protein family and function. Special consideration is given to primary or species-specific sensitization and possible cross-reactivity, because one of the most important clinical utility of MD is its ability to reveal whether the sensitization is genuine in nature (primary, species-specific) or if it is due to cross-reactivity to proteins with similar protein structures, which may help to evaluate the risk of reaction on exposure to different allergen sources. MD can be a support tool for choosing the right treatment for the right patient with the right timing. Such information will eventually give clinicians the possibility to individualize the actions taken, including an advice on targeted allergen exposure reduction, selection of suitable allergens for specific immunotherapy, or the need to perform food challenges. Nevertheless, all in vitro tests should be evaluated together with the clinical history, because allergen sensitization does not necessarily imply clinical responsiveness.

Component-resolved diagnosis from latex allergy by microarray

BACKGROUND

A positive specific IgE (sIgE) result for latex does not always mirror the clinical situation and is frequently found in individuals without overt latex allergy.

OBJECTIVE

We sought to investigate the potential of component-resolved diagnosis (CRD) of latex allergy by microarray and to assess whether the technique allows discriminating genuine allergy from asymptomatic sensitization.

METHODS

Twenty-six healthy controls without a history of latex allergy with a negative latex sIgE and skin test, 22 latex-allergic patients with a compelling history of latex allergy with a positive latex sIgE and prick test and 20 latex-sensitized individuals with a frequent asymptomatic exposure to natural rubber latex-containing devices with a negative latex skin test but a positive sIgE were also included. CRD was performed with the ImmunoCAP ISAC microarray and traditional singleplexed ImmunoCAP.

RESULTS

In all patients, the diagnosis of latex allergy could be established by the combination of recombinant latex components present on the microarray (Hev b 1, Hev b 3, Hev b 5 and Hev b 6.02). Over three-quarters of our patients were sensitized for Hev b 5 and/or Hev b 6.02. Some patients also displayed reactivity for Hev b 1 and/or Hev b 3. In contrast, none of the individuals sensitized to natural rubber latex or control individuals demonstrated IgE reactivity for rHev b 1, rHev b 3, rHev b 5 or rHev b 6.02. Three-quarters of the patients sensitized to latex displayed a positive microarray result for recombinant latex profilin (rHev b 8). In contrast to the results obtained by traditional ImmunoCAP for bromelain, almost no sensitization for cross-reactive carbohydrates was demonstrated by bromelain spotted on the microarray. CRD by traditional singleplexed ImmunoCAP showed highly comparable results.

CONCLUSION

CRD by microarray is a reliable tool for diagnosing latex allergy. In addition, the technique allows discrimination between genuine allergy and sensitization. CRD by microarray can improve the diagnosis of IgE-mediated latex allergy by discriminating between genuine allergy and sensitization. CRD by microarray is a reliable tool to diagnose latex allergy. In addition, the technique allows discrimination between a genuine allergy and simple sensitization.

Latex allergy: a model for therapy

Allergy to natural rubber latex products emerged as an important clinical condition following an increase in the use of latex gloves for barrier protection in the early 1980s. In addition to latex glove users, other high-risk groups with different latex exposure include spina bifida patients and others with multiple surgical procedures. Subjects with fruit and vegetable allergy are also at risk due to cross-reactive allergens. Following the significant advances in the identification and characterization of common aeroallergens, latex allergy was well placed to become an excellent model of therapy. Awareness of latex allergy and modes of sensitization enabled epidemiological studies to inform allergen avoidance initiatives, substantially reducing inadvertent exposure in major hospitals in Western countries. Spina bifida is often identified in utero or soon after birth, allowing vigorous latex allergen avoidance with enhanced efficacy of primary prevention. However, changing demographics of latex allergy and technological revolution in countries such as China and India are predicted to unleash a second wave of latex allergy reemphasizing the incentive for improved manufacturing procedures for latex products. The desirable high tensile strength and elasticity of natural rubber latex have made the commercial identification of good alternatives very difficult but this would also be attractive for primary prevention. In addition, an effective specific immunotherapy regimen would be valuable for selected high-risk atopic individuals. Current subcutaneous and sublingual immunotherapy schedules have been tested for treatment of latex allergy with evidence of efficacy but the risks of adverse events are high. For such potent allergens as latex, hypoallergenic but T cell-reactive preparations are required for clinical use. Identification of allergenic components of latex products, with generation of monoclonal antibodies and recombinant allergens, allowed sequence determination and mapping of T cell and B cell epitopes. Together, these reagents and data facilitated improved diagnostics and investigation of novel-specific therapeutics. Potential hypoallergenic latex preparations identified include modified non-IgE-reactive allergen molecules and short T cell epitope peptides. The co-administration of adjunct therapies such as anti-IgE or corticosteroids and of appropriate adjuvants for induction of regulatory T cell response offers promise for clinically effective, safe latex-specific vaccines.

Latex allergy risk assessment in children and adolescents with type I diabetes mellitus

An increased frequency of allergic reactions to latex has been reported in specific populations with chronic latex exposure. However, relevance of latex allergy to children and adolescents with type I diabetes mellitus (DM1) has not been studied yet. The aim of the studty is to assess latex allergy risk in children and adolescents with DM1. Thirty-nine children with DM1 and 35 controls were enrolled. In a case-control study, we applied to all subjects a standard questionnaire, and specific Immunoglobulin E (IgE) concentrations for latex, common aeroallergens, and food-allergens were measured in serum samples. Latex exposure rates by means of medical procedures, operations, and latex glove usage were not different between DM1 and controls. Symptoms due to latex exposure were not determined in both groups. Three (7.7%) subjects in DM1 tested positive for latex-specific antibodies (LSIE), whereas no subject in controls. Diabetics that tested positive for latex-specific antibodies had the disease for three, 5 and 8 years. Nine (23.1%) of diabetics, and two (5.7%) of controls were atopic (p = 0.04). In our investigation, we found that children and adolescents with DM1 are not a risk group for latex allergy, and LSIE in children with DM1 was not accompanied by symptoms of latex allergy, or, presumably, increased risk of latex anaphylaxis.

Quantitative analysis of immunoglobulin E reactivity profiles in patients allergic or sensitized to natural rubber latex (Hevea brasiliensis)

BACKGROUND

Characterized native and recombinant Hevea brasiliensis (rHev b) natural rubber latex (NRL) allergens are available to assess patient allergen sensitization profiles.

OBJECTIVE

Quantification of individual IgE responses to the spectrum of documented NRL allergens and evaluation of cross-reactive carbohydrate determinants (CCDs) for more definitive diagnosis.

METHODS

Sera of 104 healthcare workers (HCW; 51 German, 21 Portuguese, 32 American), 31 spina bifida patients (SB; 11 German, 20 Portuguese) and 10 Portuguese with multiple surgeries (MS) were analysed for allergen-specific IgE antibody (sIgE) to NRL, single Hev b allergens and CCDs with ImmunoCAP technology.

RESULTS

In all patient groups rHev b 5-sIgE concentrations were the most pronounced. Hev b 2, 5, 6.01 and 13 were identified as the major allergens in HCW and combined with Hev b 1 and Hev b 3 in SB. In MS Hev b 1 displayed an intermediate relevance. Different sIgE antibody levels to native Hevea brasiliensis (nHev b) 2 and rHev b 6.01 allowed discrimination of SB with clinical relevant latex allergy vs. those with latex sensitization. Sensitization profiles of German, Portuguese and American patients were equivalent. rHev b 5, 6.01 and nHev b 13 combined detected 100% of the latex-allergic HCW and 80.1% of the SB. Only 8.3% of the sera showed sIgE response to CCDs.

CONCLUSIONS

Hev b 1, 2, 5, 6.01 and 13 were identified as the major Hev b allergens and they should be present in standardized latex extracts and in vitro allergosorbents. CCDs are only of minor relevance in patients with clinical relevant latex allergy. Component-resolved diagnostic analyses for latex allergy set the stage for an allergen-directed immunotherapy strategy.

Latex allergy within a cohort of not-at-risk subjects with respiratory symptoms: prevalence of latex sensitization and assessment of diagnostic tools

BACKGROUND

Immunoglobluin E (IgE)-mediated hypersensitivity to natural rubber latex (NRL) is a major problem in allergy practice. Currently, the use of skin prick tests (SPTs) with latex extracts and specific IgE detection for the diagnosis of NRL allergy in suspected patients is directed to identification of risk factors. Many cases of NRL allergy remain undiagnosed due to misreporting of symptoms by the patients or lack of proper questions asked by the physician.

MATERIALS AND METHODS

A total of 6,126 subjects referred for respiratory symptoms underwent SPTs with NRL. Positive subjects were resurveyed for exposure to NRL, and specific IgE for NRL extracts and recombinant molecules was determined. Immunoblots of NRL extracts were performed to identify IgE patterns.

RESULTS

Forty-six of 3,930 sensitized subjects had a positive SPT with NRL, displaying a prevalence of NRL sensitization of 0.75% for the general and 1.2% for the sensitized population. Eleven out of 46 (23.9%) subjects could be defined as NRL asymptomatic, whereas 35 (76.1%) developed symptoms upon exposure to NRL. Specific IgE to NRL was detected for 22 (75.86%) of 29 tested sera. Seventeen out of 22 (77%) sera displayed specific IgE to recombinant allergens with most reactions to Hev b 5, Hev b 6.01 and Hev b 6.02. Immunoblots of NRL extract fractions with patients' sera showed heterogeneous patterns.

CONCLUSIONS

SPTs with NRL extract should be routinely performed in patients with respiratory symptoms. Hev b 5, Hev b 6.01 and Hev b 6.02 are the most important allergens, but further characterization of NRL extracts is needed to identify novel allergens and to clarify the role of crossreactive carbohydrate determinants.