Clinical and laboratory-based methods in the diagnosis of natural rubber latex allergy

Perioperative hypersensitivity in children: A prospective multidisciplinary study

BACKGROUND

There are few studies of perioperative hypersensitivity reactions in children. The diagnosis of perioperative hypersensitivity reactions may be under estimated because it is difficult to recognize the reactions. Anaphylaxis may go unnoticed because of patient unconsciousness. Urticaria may be missed due to sterile drapes. The aim of this study was to prospectively evaluate perioperative hypersensitivity reactions.

METHODS

In this prospective study, patients with suspected perioperative hypersensitivity reactions aged 0-18 years who underwent surgery at the Department of Pediatric Surgery, Cerrahpasa Faculty of Medicine, between 2019 and 2021 were investigated. Suspected reactions in the perioperative period were graded according to the Ring and Messmer scale. Patients with suspected reactions were examined 4-6 weeks after the reaction. If necessary, specific IgE and basophil activation tests were performed. Reactions of grades III-IV were considered anaphylaxis. If one test modality was strongly positive and there was a relevant time point or repeated allergic reactions, or at least two test modalities were positive, hypersensitivity was confirmed. In all patients, serum tryptase levels were analyzed at the time of the reaction, 2 h after the reaction, and 4-6 weeks after the reaction as part of the allergic evaluation.

RESULTS

A total of 29 patients (8 female, 21 male) suspected of having an intraoperative reaction during the study were included in the analysis. Perioperative hypersensitivity reactions were noted in 1 patient. The incidence of perioperative hypersensitivity reactions was reported to be 0.03% (n = 1/2861). While anaphylaxis was confirmed in 1 patient, 5 patients were considered possible anaphylaxis cases.

CONCLUSION

Perioperative hypersensitivity reactions can be life-threatening and may recur with further administration. Collaboration between pediatric surgeons, anesthesiologists, and allergists can prevent further reactions. All suspected cases should be evaluated by an experienced allergist soon after the initial reaction.

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.

Update on latex allergy: New insights into an old problem

Despite the efforts made to mitigate the consequences of this disease, natural rubber latex allergy (NRLA) continues to be a global health problem and is still considered one of the main worries in the working environment in many countries throughout the world. Due to thousands of products containing latex, it is not surprising that the current statistics suggest that prevalence remains high among healthcare workers and susceptible patients. In developed countries, reduction in the prevalence of IgE-mediated allergy to latex proteins from gloves may lead to lax attention by health care personnel. On the other hand, this situation is different in developing countries where there is a lack of epidemiological data associated with a deficit in education and awareness of this issue. The aim of this review is to provide an update of the current knowledge and practical recommendations regarding NRLA by allergologists from different parts of the world with experience in this field.

Profile Shift in Latex Sensitization over the Last 20 Years

BACKGROUND

Natural rubber latex (NRL) allergy is commonly diagnosed according to medical history, skin allergy tests, and serological analyses. However, skin tests are increasingly being abandoned because of (i) their time-consuming nature, (ii) latex preparations for skin tests being not commercially available, and (iii) the use of in-house prepared test solutions is becoming ever more difficult due to increasing regulatory hurdles. In this light, we have evaluated differences in the profiles of current and former patients with suspected latex allergy.

METHODS

Sera of skin test-positive patients from a historic cohort (1995-2001, n = 149 patients) and currently (2014-2015, n = 48 patients) were simultaneously analyzed for specific IgE to latex by ImmunoCAP. If the serological screening was positive (≥0.35 kU/L), component-resolved diagnostics including profilins and cross-reactive carbohydrate determinants (CCDs) were performed.

RESULTS

In contrast to 88% (131/149) of the skin test-positive patients from the 1990s, only 51.1% (24/47) of the current cohort were found positive for specific IgE to latex. While 48.3% (72/149) of the patients had a convincing positive history in the 1990s, current skin test-positive patients rarely reported a relevant medical history (8.5%, 4/47). Specific IgE levels to latex were significantly higher in former patients with suspected latex allergy (p < 0.001) than in former sensitized individuals without allergy. However, this significant difference was lost in current allergic and sensitized patients with positive skin tests.

CONCLUSION

Sensitization profiles in patients with latex allergy have changed significantly over the last 2 decades. Discrimination between NRL sensitization and clinical allergy remains a diagnostic challenge. Our data highlight the need for a combination of all 3 criteria, i.e., patient history, skin test, and analysis of specific IgE, for a correct diagnosis of latex allergy.

Conversion to Low-Protein, Powder-Free Surgical Gloves: Is it Worth the Cost?

This study was conducted to determine changes in overall costs associated with conversion to powder-free gloves including cost of workers' compensation cases for natural rubber latex (NRL)-related symptoms and health care workers' glove satisfaction. The study, a 2–year, longitudinal design with retrospective and prospective aspects, was developed to determine health care worker use of powder-free, low-protein NRL gloves, sensitization, cost, and glove satisfaction. Informed consent was obtained from 103 health care workers. Prior to glove conversion, nearly one-half (44%, 36 of 82) of the operating room staff reported symptoms related to NRL exposure. At the end of the 14–month data collection period, only 27% (22 of 82, McNemar test = .007) reported symptoms related to NRL exposure. Additionally, a cost savings of $10,000 per year for gloves was evident with reports of increased user satisfaction. This study demonstrated that conversion to the use of powder-free, low-protein NRL gloves not only reduces health care worker NRL symptoms, but also positively affects the costs of glove purchases and workers' compensation.

Risk and safety requirements for diagnostic and therapeutic procedures in allergology: World Allergy Organization Statement

One of the major concerns in the practice of allergy is related to the safety of procedures for the diagnosis and treatment of allergic disease. Management (diagnosis and treatment) of hypersensitivity disorders involves often intentional exposure to potentially allergenic substances (during skin testing), deliberate induction in the office of allergic symptoms to offending compounds (provocation tests) or intentional application of potentially dangerous substances (allergy vaccine) to sensitized patients. These situations may be associated with a significant risk of unwanted, excessive or even dangerous reactions, which in many instances cannot be completely avoided. However, adverse reactions can be minimized or even avoided if a physician is fully aware of potential risk and is prepared to appropriately handle the situation. Information on the risk of diagnostic and therapeutic procedures in allergic diseases has been accumulated in the medical literature for decades; however, except for allergen specific immunotherapy, it has never been presented in a systematic fashion. Up to now no single document addressed the risk of the most commonly used medical procedures in the allergy office nor attempted to present general requirements necessary to assure the safety of these procedures. Following review of available literature a group of allergy experts within the World Allergy Organization (WAO), representing various continents and areas of allergy expertise, presents this report on risk associated with diagnostic and therapeutic procedures in allergology and proposes a consensus on safety requirements for performing procedures in allergy offices. Optimal safety measures including appropriate location, type and required time of supervision, availability of safety equipment, access to specialized emergency services, etc. for various procedures have been recommended. This document should be useful for allergists with already established practices and experience as well as to other specialists taking care of patients with allergies.

Anaphylaxis avoidance and management: educating patients and their caregivers

Anaphylaxis is an increasingly prevalent problem in westernized countries. Therefore, it is of utmost importance that the increasing numbers of patients at risk for anaphylaxis receive proper education on the etiology and risk factors as well as appropriate treatment of anaphylaxis with epinephrine. The physician’s role is crucial in order to educate the patients and care takers on effective measures to prevent anaphylaxis and empower them to take charge of early recognition and proper management of an anaphylactic reaction to prevent poor outcomes. This review summarizes the clinical presentation, triggers, avoidance, and management of anaphylaxis.

LATEX sensitization in elderly: allergological study and diagnostic protocol

BACKGROUND

The prevalence of latex allergy varies according to the population studied from 3% to 64%. No data exist in the present literature about elderly people because they were not considered among populations at risk. We report a retrospective observational study of 88 elderly patients of our centre of Dermatology and Allergology at Policlinico Umberto I, University of Rome, Sapienza.

RESULTS

First and second level diagnostic tests showed latex positivity in 11,4% of patients studied for latex allergy in the elderly population.

CONCLUSIONS

Our study demonstrates a prevalence of elderly-latex sensitization of 11,4%, showing that allergy to latex is a growing disease that can occur at any age. So, we propose these patients as an additional risk category for latex allergy.

Diagnostic value of the ISAC(®) allergy chip in detecting latex sensitizations

PURPOSE

Latex allergy can be diagnosed by different test methods such as IgE quantification, Western blot, cellular antigen stimulation test (CAST), and in vivo methods [e.g. skin prick test (SPT)]. Phadia provides two modern methods using recombinant latex allergens: ImmunoCAP(®) and the Immuno Solid-phase Allergen Chip (ISAC(®)), which enables simultaneous determination of specific IgE against five latex allergens. We compared the diagnostic sensitivity of the ISAC(®) test kit and the conventional Hev b 5-spiked ImmunoCAP(®) latex extract.

METHODS

Forty sera were sampled from subjects with suspected natural rubber latex (NRL) allergy. These patients had positive SPT to NRL extract, positive NRL Western blots, and positive results in the CAST. All sera were analysed using the ISAC(®) and recombinant NRL ImmunoCAP(®) allergens and compared to the results of 20 negative control sera.

RESULTS

Only 22 of the 40 subjects (55 %) showed positivity to at least one latex allergen on the ISAC(®) (sensitivity ISAC(®) 55 %). The sensitivity of the ImmunoCAP(®) latex extract was 70 %. The most frequently detected sensitization was against Hev b 6.01 (n = 12). When the serum samples were tested with all recombinant ImmunoCAP(®) allergens, three additional sensitizations against latex could be detected compared to the ISAC(®).

CONCLUSIONS

Microarrays do offer many potential benefits such as elegant simultaneous determination of sensitizations against different NRL allergens with minimal amounts of serum. However, a negative NRL test result should be regarded with caution and at least be confirmed by other in vitro methods.

Analysis of available diagnostic tests for latex sensitization in an at-risk population

BACKGROUND

Lack of a Food and Drug Administration (FDA)-approved skin testing reagent for latex allergy in the United States requires reliance on patient history and serologic assays for diagnosis.

OBJECTIVE

To determine the diagnostic sensitivity, specificity, and predictive values of an FDA-cleared antilatex IgE serology test and an enzyme-linked immunosorbent assay (ELISA) with various sources of latex protein antigens in an at-risk but unselected population of health care workers.

METHODS

Health care workers underwent duplicate latex and serologic testing for latex specific IgE with the CAP assay and ELISA from June 1, 1998, through December 31, 2002. Logistic regression with receiver operating characteristic curve analysis determined the values, resulting in 98% and 99% specificity for the CAP assay and ELISA, respectively.

RESULTS

Results of paired skin and serologic tests were available for 792 participants. Forty duplicate skin test results (5%) were positive. For the CAP assay, sensitivity was 35%; specificity, 98%; positive predictive value, 48.3%; and negative predictive value, 96.6%. ELISA demonstrated similar results. Multivariable logistic regression yielding a 98% or 99% specificity for the various ELISAs demonstrated that the adjusted odds of a positive skin test result significantly increased with positive CAP assay and ELISA results using a powdered glove extract.

CONCLUSIONS

The performance of the FDA-cleared antilatex IgE serologic test for latex allergy has much lower sensitivity than previously reported. This finding confirms that this serologic test should be used only for patients with a history of latex allergy and not for screening the population with a low prevalence of latex sensitization.

Curativo de biomembrana vegetal e hipersensibilidade

FUNDAMENTOS: A biomembrana vegetal do látex da seringueira Hevea brasiliensis tem sido usada como curativo para úlceras cutâneas. OBJETIVOS: Avaliar a segurança da biomembrana vegetal como curativo em relação à hipersensibilidade ao látex. MÉTODOS: Foram selecionados pacientes com úlceras cutâneas constituindo-se os grupos: controle - baixa exposição profissional ao látex (n=17); alta exposição profissional (n=14); ulcerados em uso da biomembrana vegetal (n=13); ulcerados-controle sem uso da biomembrana vegetal (n=14) e casos novos (n=9), submetidos à avaliação pré e após 3 meses de uso da biomembrana vegetal. Todos foram submetidos à avaliação clínico-epidemiológica quanto à hipersensibilidade ao látex e IgE específica (UniCap®), e os grupos controle e controle exposto ao látex ao "patch test". RESULTADOS: A história de hipersensibilidade foi positiva em 64,7% dos pacientes do grupo-controle, 71,4% do controle exposto ao látex, 61,5% dos ulcerados em uso da biomembrana vegetal, 35,7% dos ulcerados-controle, e apenas 22,2% no grupo casos novos. Ao teste de contato dos grupos controle e controle exposto ao látex, apenas um indivíduo do grupo C (baixo contato) apresentou eritema na primeira leitura, negativando-se na segunda. A média de contato com látex no grupo-controle exposto ao látex foi de 3,42 horas/dia. No ensaio fluoroimunoenzimático, a grande maioria dos soros foi classificada como zero (variação 0 a 6). Nenhum soro recebeu classificação acima de 2, não sendo considerada classificação significante para hipersensibilidade (classificação > 4). CONCLUSÃO: A biomembrana vegetal mostrou-se segura como curativo, pois não induziu reações de hipersensibilidade entre os voluntários submetidos ao "patch test", nem entre os usuários da biomembrana vegetal, como demonstrado clinica e imunologicamente pela dosagem de IgE.

Perioperative Latex Allergy

The prevalence of latex allergy varies greatly depending on the population studied and the methods used to detect sensitization. Subjects considered to be at high risk for latex allergy are rubber industry workers, children with spina bifida and urological abnormalities, children undergoing multiple surgical procedures and with urinary catheterization, health care workers and people with food allergy (latex fruit syndrome). In this paper we report a review of latex proteins, the symptoms of latex allergy, diagnosis and management in subjects with latex allergy.

Latex medical gloves: time for a reappraisal

Many hospitals have implemented policies to restrict or ban the use of devices made of natural rubber latex (NRL) in healthcare as precautionary measures against the perceived risk of NRL allergy. Changes in glove technology, progress in measuring the specific allergenic potential of gloves and a dramatic decrease in the prevalence of NRL allergies after interventions and education prompted us to revisit the basis for justifiable glove selection policies. The published Anglophone literature from 1990 to 2010 was reviewed for original articles and reviews dealing with the barrier and performance properties of NRL and synthetic gloves and the role of glove powder. The review shows that NRL medical gloves, when compared with synthetic gloves, tend to be stronger, more flexible and better accepted by clinicians. The introduction of powder-free gloves has been associated with reductions in protein content and associated allergies. Recently, new methods to quantify clinically relevant NRL allergens have enabled the identification of gloves with low allergenic potential. The use of low-protein, low-allergenic, powder-free gloves is associated with a significant decrease in the prevalence of type I allergic reactions to NRL among healthcare workers. Given the excellent barrier properties and operating characteristics, dramatically reduced incidences of allergic reactions, availability of specific tests for selection of low-allergen gloves, competitive costs and low environmental impact, the use of NRL gloves within the hospital environment warrants reappraisal.

The diagnosis and management of anaphylaxis practice parameter: 2010 update

These parameters were developed by the Joint Task Force on Practice Parameters, representing the American Academy of Allergy, Asthma & Immunology (AAAAI); the American College of Allergy, Asthma & Immunology (ACAAI); and the Joint Council of Allergy, Asthma and Immunology. The AAAAI and the ACAAI have jointly accepted responsibility for establishing "The Diagnosis and Management of Anaphylaxis Practice Parameter: 2010 Update." This is a complete and comprehensive document at the current time. The medical environment is a changing environment, and not all recommendations will be appropriate for all patients. Because this document incorporated the efforts of many participants, no single individual, including those who served on the Joint Task Force, is authorized to provide an official AAAAI or ACAAI interpretation of these practice parameters. Any request for information about or an interpretation of these practice parameters by the AAAAI or ACAAI should be directed to the Executive Offices of the AAAAI, the ACAAI, or the Joint Council of Allergy, Asthma and Immunology. These parameters are not designed for use by pharmaceutical companies in drug promotion.

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.

Alergia ao látex em profissionais de saúde de São Paulo, Brasil

FUNDAMENTOS: Alergia ao látex é comum em trabalhadores da saúde, resultando em absenteísmo e afastamento das atividades profissionais. Há no Brasil poucos estudos publicados sobre o assunto. Enquanto na população geral a prevalência de alergia ao látex é menor que 2%, nos profissionais de saúde pode chegar a 30%. OBJETIVO: Estudar a prevalência de alergia ao látex em profissionais de saúde do Hospital do Servidor Público Estadual de São Paulo. MÉTODOS: Foi aplicado questionário aberto a profissionais que têm contato com luvas de borracha em todos os serviços do hospital. Foi colhido sangue daqueles que referiram sintomas e dosado anticorpo IgE específico por meio do ImmunoCAP. Para análise estatística utilizaram-se porcentagens, tabelas e teste qui-quadrado. RESULTADOS: Foram distribuídos 2.349 questionários, e respondidos 1.045, dos quais 129 referiram correlação entre uso de látex e sintomas sugestivos de alergia, e 54 permitiram a coleta de sangue para determinação de IgE específica. Neste grupo houve dois casos em que foi demonstrado anticorpo específico, estabelecendo-se prevalência de 3,7% de alergia ao látex. Fatores como gênero, profissão, freqüência de contato com luvas, setor de trabalho e antecedentes de atopia foram relacionados com maior prevalência de alergia ao látex. CONCLUSÃO: A prevalência de alergia ao látex encontrada foi de 3,7%.

Percutaneous reactivity to natural rubber latex proteins persists in health-care workers following avoidance of natural rubber latex

BACKGROUND

Long-term avoidance of natural rubber latex [Hevea brasiliensis (Hev b)] is currently recommended for health-care workers (HCWs) with established natural rubber latex (NRL) allergy. Percutaneous sensitivity to eight Hev b NRL allergens was evaluated in HCWs in 2000. To date, no studies have evaluated the longitudinal effects of NRL avoidance on percutaneous sensitivity to NRL allergens.

OBJECTIVE

The aims of this study were to evaluate changes in percutaneous reactivity to non-ammoniated latex (NAL) and NRL allergens in HCWs 5 years after a recommendation to avoid NRL and to evaluate factors that predict the persistence of in vivo sensitivity to NAL and NRL allergens.

METHODS

Skin prick testing was performed with NAL, seven NRL allergens (Hev b 1, 2, 3, 4, 6.01, 7.01, and 13), and recombinant Hev b 5 (rHev b 5) in 34 HCWs who were initially evaluated in 2000 for occupationally related NRL allergy. Serial 10-fold dilutions of NAL and NRL allergens were employed in skin testing. Sera from the HCWs were assayed for latex and enhanced latex (rHev b 5-enriched allergosorbent)-specific IgE antibodies using the ImmunoCAP assay.

RESULTS

The prevalence of work-related symptoms significantly decreased between 2000 and 2005 with avoidance of NRL (P<0.05). A >/=100-fold reduction in percutaneous sensitivity to Hev b 2 and Hev b 7 was less likely in those with prior history of systemic reactions to NRL (P=0.0053), reported history of reaction to cross-reactive foods (P=0.014), continued local reactions to NRL gloves (P<0.0001), or high NRL glove exposure since the initial study (P=0.0075). The diagnostic sensitivity and specificity of the latex-specific IgE serology was 54% and 87.5%, respectively, in comparison with NAL skin tests. The addition of rHev b 5 to the ImmunoCAP (enhanced latex) allergosorbent altered the diagnostic sensitivity and specificity of the ImmunoCAP to 77% and 75%, respectively.

CONCLUSION

While symptoms may resolve quickly with NRL avoidance therapy, detectable IgE indicating continued sensitization remains beyond 5 years, and thus continued avoidance of NRL should be recommended.

Anaphylaxis during anaesthesia: diagnostic approach

Correct management of anaphylaxis during anaesthesia requires a multidisciplinary approach with prompt recognition and treatment of the acute event by the attending anaesthesiologist, and subsequent determination of the responsible agent(s) with strict avoidance of subsequent administration of all incriminated and/or cross-reacting compounds. However, correct identification of the causative compound(s) and safe alternatives is not always straightforward and, too often, not done. This review is not intended to discuss acute management of anaesthesia-related anaphylaxis but summarizes the major causes of anaphylaxis during anaesthesia and the diagnostic approach of this rare but potentially life-threatening complication. Apart from general principles about the diagnostic approach, history taking and importance of tryptase quantification, more specific confirmatory diagnostic procedures are organized on the basis of the major causes of perioperative anaphylactic reactions.

Generation of Allergen-Enriched Protein Fractions of Hevea brasiliensis Latex for in vitro and in vivo Diagnosis

BACKGROUND

The latex of Hevea brasiliensis trees contains a complex proteome that includes a range of allergenic proteins. Current latex extracts that are used for the diagnosis of latex allergy still lack important allergens. We aimed to devise a production process for an improved reagent that would ideally contain the complete latex allergome.

METHODS

Latex C-serum was fractionated by ammonium sulfate precipitation, and B- and C-serum proteins were then separated by anion exchange chromatography. Proteins eluting within defined salt concentration ranges were pooled into six final fractions. Fractions were evaluated by two-dimensional electrophoresis and subsequent IgE immunoblot for their spectrum of allergens. The presence of the most important latex allergens in the fractions was checked by Western blot analyses. Each fraction was further evaluated by skin prick test (SPT).

RESULTS

Reproducibility of the preparation method was demonstrated with two batches of latex. Comparison of latex B- and C-serum to the six fractions showed a remarkable increase in the number of detectable allergens in the fractions. The presence of the latex allergens Hev b 1-8 and Hev b 13 in the fractions was demonstrated. In SPTs, the fractions produced wheal-and-flare reactions comparable to commercial latex extracts.

CONCLUSIONS

This method provides reproducible latex protein fractions of high allergen content for the diagnosis of latex allergy.

Latex specific IgE: performance characteristics of the IMMULITE 2000 3gAllergy assay compared with skin testing

BACKGROUND

In the absence of a US Food and Drug Administration (FDA)-cleared latex skin testing reagent, in vitro tests remain important for the diagnosis of latex allergy.

OBJECTIVE

To evaluate the performance characteristics of IMMULITE 2000 3gAllergy (Immulite), a third-generation, FDA-cleared, continuous random-access immunoanalyzer, for the quantification of latex specific IgE.

METHODS

Stored serum samples (N = 201) from patients classified as having positive or negative latex puncture skin test results were measured for latex specific IgE levels using Immulite, and these data were compared with historical results from 3 second-generation, FDA-cleared IgE antilatex assays (AlaSTAT [Ala], AutoCAP [CAP], and HY*TEC enzyme immunoassay [HT]).

RESULTS

The diagnostic performances of the CAP, Ala, and Immulite assays (> or = 0.35 kU/L cutoff value) were equivalent in sensitivity and specificity (P > .05). The HT assay (> or = 0.05 kU/L cutoff value) was more sensitive and less specific (P < .05). Immulite (> or = 0.10 kU/L cutoff value) had greater sensitivity than Ala and CAP and greater specificity than HT (P < .05 for both). Diagnostic efficiency was greater for Immulite than for CAP, Ala, and HT (P < .05).

CONCLUSIONS

The Immulite system is superior in diagnostic performance, especially at the 0.10 kU/L or greater cutoff level, for the diagnosis of latex allergy compared with older, second-generation assays. Immulite still misclassifies 15.5% of puncture skin test-positive individuals as negative for latex specific IgE. Compared with second-generation assays, Immulite represents a technological advance, with enhanced speed and less operator intervention.

Latex allergen IgE assays in the assessment of Veterans Affairs health care workers

BACKGROUND

A previous multicenter study of Veterans Affairs health care workers evaluated hospital participants for latex hypersensitivity. Well-defined groups from that study allowed us to explore the diagnostic utility of newer antilatex allergen IgE immunoassays in the present study.

OBJECTIVES

To determine whether an enhanced CAP (ENHCAP) assay or an enzyme-linked immunosorbent assay (ELISA) identifies latex glove symptomatic individuals with antilatex allergen IgE that had not been detected by the CAP assay used in the original study and to determine the specificity of the ENHCAP assay.

METHODS

The ELISA measured IgE antibody to Malaysian nonammoniated natural rubber latex extract (MNA), Hev b1, Hev b5, and Hev b6. Four patient groups were tested: confirmed latex glove allergic, latex glove symptomatic, latex glove sensitized/asymptomatic, and latex glove nonallergic.

RESULTS

The ENHCAP assay and the MNA ELISA were highly concordant with the original CAP assay. In the subgroup with latex glove symptoms that were previously negative by the CAP assay, the ENHCAP assay value was elevated in 7 (11%) of 64 samples, only 3 of which were class 2 or higher. The MNA ELISA result was positive in only 4 (6%) of these 64 samples, and 3 of these were fractionally above the cutoff value for this assay.

CONCLUSIONS

The ENHCAP assay and the MNA ELISA identified a few additional positive individuals in the group that was latex glove symptomatic and originally CAP assay negative. The ENHCAP assay and the MNA ELISA produced only a modest improvement in diagnostic sensitivity over that of the original CAP assay.

Hevea brasiliensis latex allergens: current panel and clinical relevance

Latex allergy has been studied in detail in Europe and the US over the past two decades, resulting in specific guidelines that succeeded in reducing its incidence in high-risk populations within the medical field. How these developments have affected high-risk populations outside the health care scenario is an important unanswered question. In addition, a second wave of latex allergy may occur in nations that are striving to attain higher economic and technologic standards, including population-dense countries such as China. Therefore, the application of Hevea allergens in novel diagnostic assays and the development of specific latex immunotherapy will provide new opportunities for latex allergy research. In this review, we summarize current knowledge on the immunological properties of the 13 officially accepted Hevea brasiliensis latex allergens.

Latex allergy: diagnosis and management

Latex allergy is an IgE-mediated immediate hypersensitivity response to natural rubber latex (NRL) protein with a variety of clinical signs ranging from contact urticaria, angioedema, asthma, and anaphylaxis. Major allergens include dipped latex products such as gloves and balloons. In highest risk for NRL allergy are patients with spina bifida, but health care workers and others who wear latex gloves are also at risk. NRL allergic patients may also react to fruits/foods, especially banana, kiwi, and avocado. Diagnosis is made by a positive latex RAST and/or skin prick test or challenge test to NRL. Allergen avoidance and substitution and the use of latex-safe devices including synthetic gloves (vinyl, synthetic polyisoprene, neoprene, nitrile, block polymers, or polyurethane) are essential for the affected patient. Accommodation in the workplace may include the use of powder-free, low-allergen NRL gloves or synthetic gloves. These preventive measures have significantly reduced the prevalence of reported reactions to NRL. Hyposensitization is not yet feasible.

Confirmation of the diagnosis of natural rubber latex allergy by the Basotest method

BACKGROUND

The flow cytometry CD63-based basophil activation test (Basotest has already been validated for the diagnosis of immediate-type allergy such as venom, house dust mite or cypress pollen allergies. The aim of this study was to evaluate the performance (specificity and sensitivity) of Basotest in the diagnosis of natural rubber latex allergy.

METHODS

We included 46 latex allergic patients (clinical symptoms of latex allergy, positive latex skin prick tests and/or latex specific IgE) and 33 control subjects and performed Basotest on all subjects.

RESULTS

The sensitivity and specificity of Basotest were 84.8 and 87.9%, respectively, when we considered the theoretic cut-off at 15% of CD63-positive cells. Using ROC curves, the optimal cut-off was evaluated at 22%, for which sensitivity and specificity were 79.3 and 96.7%, respectively.

CONCLUSION

The Basotest is a reliable test in addition to clinical history and tests already validated (such as skin prick tests and specific IgE) to confirm the diagnosis of natural rubber latex allergy.

Drug-eluting stents: caution and concerns for long-term outcome

Recent publications on drug-eluting stents (DES) report a significant reduction in restenosis rates as compared to bare metal stents in patients mostly with single vessel disease. We have recently observed however, late stent thrombosis following CYPHER DES implantation. The patient developed a hypersensitivity reaction around stent struts limited to the polymer with aneurysmal dilatation and extensive inflammation of the arterial wall in the absence of vascular healing. This incidence promotes a cautionary view and perhaps supports the use of DES only in high-risk patients.

Anaphylaxis during surgical and interventional procedures

OBJECTIVE

To describe the current evidence-based knowledge of the causes, diagnostic evaluation, and treatment of patients with anaphylaxis associated with surgical and interventional procedures.

DATA SOURCES

Articles published between 1966 and 2003 were identified in MEDLINE using the keywords anaphylactoid, anaphylaxis, anesthetics, antibiotics, cephalosporins, contrast media, colloids, flow cytometry, hypersensitivity, latex, neuromuscular depolarizing agents, neuromuscular nondepolarizing agents, penicillins, radioallergosorbent test, skin test, and vancomycin. Additional studies were identified from article reference lists.

STUDY SELECTION

Relevant, peer-reviewed original research articles and reviews.

RESULTS

Neuromuscular blocking agents, natural rubber latex, antibiotics, and induction agents are the most common causes of anaphylaxis during surgical and interventional procedures. Colloids, opioids, and radiocontrast media probably account for less than 10% of all reactions. Newer agents implicated in anaphylaxis include isosulphan blue and chlorhexidine. Skin tests are useful for evaluating allergic reactions to anesthetic agents and penicillins and for selecting alternative agents. Skin testing and specific IgE measurements for latex vary in allergen standardization and sensitivity and specificity, respectively. Flow cytometric allergen stimulation tests show promise in differentiating allergic from idiosyncratic ("pseudoallergic") reactions. Drug desensitization has been shown to be useful for penicillin anaphylaxis. Premedication with histamine receptor antagonists and corticosteroids helps prevent or attenuate radiocontrast media reactions.

CONCLUSIONS

Anaphylaxis during surgical and interventional procedures may be difficult to evaluate because of the rapid, successive use of multiple drugs or diagnostic agents. Careful analysis of anesthetic records and diagnostic tests for all the putative agents are necessary to ensure a complete evaluation.

Prevention of anaphylactic reactions to anaesthetic drugs

Although screening tests to prevent anaphylaxis during anaesthesia have been advocated, such tests are unlikely to have significant impact on reducing the incidence of anaphylaxis during anaesthesia. This is due to the low prevalence of the disease, the diversity of drugs used in anaesthesia and the incidence of false positive and negative tests. The suggested risk factors of allergy, i.e. atopy, asthma, family history, female sex, previous exposure, vasectomy, use of zinc protamine sulfate insulin and allergy to cosmetics, eggs, fish and non-anaesthetic drugs are not valid. Although all have theoretical or real associations with anaphylaxis during anaesthesia the majority of patients with such a history undergo uneventful anaesthesia. Fruit allergy, anaphylaxis to cephalosporins and penicillin, barbiturate allergy, gelatin allergy and allergy to metabisulphite and eggs require consideration in avoiding particular drugs. The incidence of anaesthetic anaphylaxis can be reduced by avoiding latex exposure in patients with spina bifida or latex allergy, and preventing second reactions in patients with a history of anaphylaxis, or major undiagnosed or undocumented adverse events during anaesthesia. Determining the cause of an adverse event and the drug responsible, and adequately communicating those findings can reduce second reactions. Avoiding neuromuscular blocking drugs (NMBDs) in patients who have reacted to an NMBD, and use of non-intravenous techniques should also reduce the incidence of second reactions. Desensitisation, and blocking with monovalent quaternary ammonium compounds may allow improved safety of NMBDs and pretreatment with antihistamines and corticosteroids may block or ameliorate the severity of reactions, but there is currently little evidence to support their routine use.

Age-associated issues in preoperative evaluation, testing, and planning: pediatrics

The author has reviewed recent developments in preoperative assessment and testing, emphasizing issues that are of greatest concern in pediatric patients. Attention to these areas during the process of preoperative preparation and appropriate communication of conditions that may contribute to increased peri-operative risk will provide greater predictability for families, surgeons, and operating room staff. This predictability is an important component to improved patient or family satisfaction and operating room efficiency.

Approaches to testing for food and chemical sensitivities

Testing for food and chemical sensitivities usually becomes necessary as part of the evaluation of otolaryngology patients who have chronic illness. The more complex the patient, and the more recalcitrant the problem is to treatment, the more likely it is that allergies, and especially food or chemical sensitivities, are involved in the pathogenesis of the illness. Failure to consider all major allergen contacts, including foods and chemicals, can lead to inadequate therapy. Similarly, failure to understand total allergic and oxidant load and the effects of chemical toxicity can lead to inappropriate or ineffective treatment. Clinically, food allergies occur in two different types: immediate, anaphylactic, fixed reactions and delayed, chronic, cyclic reactions. Different test methods have been developed for the two types. Fixed food allergies can be safely and efficiently detected by in vitro specific IgE or histamine release tests. Cyclic food allergies are best detected by either oral food challenges or by the IPDFT test. Choosing the best test for a particular patient requires a clear understanding of the two food allergy types and how their clinical presentations differ. Other tests for food allergies are compared and contrasted with these primary tests. Chemical sensitivity also occurs in two different clinical types: allergic, and toxic. True allergy to chemical haptens, either type I, IgE-mediated, or type IV, delayed hypersensitivity, occurs with significant frequency but is often unsuspected. Chemical toxicity can be caused by the aftereffects of an acute exposure or as a result of chronic, low-level exposure, but is even more frequently unsuspected and will not be diagnosed without a high index of suspicion. Both types of chemical sensitivity need to be addressed in any patients who have either a high allergen or chemical exposure load [105]. Either in vitro or in vivo tests can be used for chemical allergy detection; the advantages of each are outlined. Chemical toxicity screening tests are available and useful but do not detect all possible toxicants. Definitive toxic chemical tests usually require specialized laboratory facilities and expert consultation, for which possible sources are specified. The most important point in testing for food or chemical sensitivity is to be aware that food or chemical sensitivity can be contributing to a specific patient's clinical problems. Only then can appropriate investigations be undertaken to understand and then, perhaps, to intervene successfully in that illness.

Latex allergy

Allergy to natural rubber latex affects people routinely exposed to rubber products. Groups thought to be at highest risk include atopics, health care workers, rubber industry workers, and individuals who have undergone multiple surgical procedures, especially those with spina bifida. Allergy to latex is a type I, immediate, IgE-mediated reaction that can lead to anaphylaxis and death. The prevalence, risk factors, clinical manifestations, diagnosis, and management of latex allergy are summarized in this review.

A Review of Natural‐Rubber Latex Allergy in Health Care Workers

This brief review of natural-rubber latex (NRL) allergy in health care workers (HCWs) includes the definition of NRL allergy and data on its epidemiology, pathogenesis, diagnostic algorithm, management, long-term outcomes, economic impact, cost-effectiveness of changing facilities to a latex-free environment, and prevention. The data presented suggest that an individual with type I or type IV hypersensitivity to NRL should be able to continue to work in the workplace with careful evaluation and reasonable accommodations. Reducing exposure to latex is a safe and more economical alternative to complete removal of the individual from the place of employment. The use of low-allergen, nonpowdered NRL gloves substantially reduces airborne exposure to latex in most health care settings.

Allergic reactions occurring during anaesthesia: diagnostic approach

Anaphylactic and anaphylactoid reactions to anaesthetic and associated agents used during the perioperative period have been increasingly reported during the last 3 decades. The frequency of life-threatening hypersensitivity reactions occurring during anaesthesia has been estimated to vary between 1/1.000 and 1/25.0000 procedures, with muscle relaxants being involved in almost three quarters of the cases. The mortality from these reactions is in the range of 3-6%. Nowadays, natural rubber latex also accounts for a significant number of perioperative anaphylaxis, particularly in children. Clinical manifestations do not allow to differentiate between IgE-mediated anaphylaxis and anaphylactoid reactions resulting from non-specific mediator release. Successful management of these patients requires multidisciplinary approach and includes prompt recognition and stabilisation of the acute event by the attending anaesthetist, determination of the responsible agent(s) with avoidance of subsequent administration of incriminated compound(s). The latter is based upon correct identification of the responsible drug and potentially cross-reactive compounds by the allergist and requires a detailed review of the anaesthetic report as well as appropriate in vitro and in vivo allergy tests. At present, the overall performance of skin tests makes them the "gold standard" for diagnosis of muscle relaxant-induced perioperative hypersensitivity reactions. In addition, given their good negative predictive value, skin tests have been proven to be a useful tool to tailor the appropriate therapeutic alternative. For other compounds diagnosis is more difficult but newer techniques such as analysis of in vitro activated basophils can be helpful.

23. Clinical laboratory assessment of IgE-dependent hypersensitivity

This chapter reviews clinical and laboratory analyses that aid in the diagnosis and management of human allergic (IgE-dependent) diseases. The diagnostic algorithm for immediate-type hypersensitivity begins with a thorough clinical history and physical examination. Once signs and symptoms compatible with an allergic disorder have been identified, a skin test and/or blood test for allergen-specific IgE antibodies may serve as primary confirmation to strengthen the diagnosis. Puncture and intradermal skin testing provide a biologically relevant immediate-type hypersensitivity response in the skin, with resultant wheal and flare reactions within 15 minutes of allergen application. Bleeding, dermatographism, and antihistamines may confound the quality of the skin test. Allergen-specific IgE antibody may also be detected in the blood using a radioallergosorbent test (RAST). Nonisotopic "second-generation" RAST-type assays have evolved to provide more quantitative, sensitive, precise IgE antibody results. In vivo provocation tests may serve as secondary confirmatory tests when the clinical history is discordant with a primary IgE antibody test result. The multiallergen screen is a qualitative RAST-type assay that detects specific IgE antibody to approximately 15 allergens that evoke a large majority of aeroallergen or food-related allergic disorders. Other useful serological assays performed in the diagnostic allergy laboratory include total serum IgE, Hymenoptera venom-specific IgG antibody, IgG precipitins for organic dusts, mast cell tryptases, and the venom RAST inhibition test. Above all, in vivo or laboratory confirmatory test results that are inconsistent with the clinical history should be repeated as for any laboratory assessment.