One of the rubber latex allergens is a lysozyme

Alergia ao látex e a frutas em profissionais da área da saúde

INTRODUÇÃO: A alergia ao látex tornou-se um risco crescente aos indivíduos expostos, como os profissionais da área da saúde, tendo como agravo a associação com hipersensibilidade a vários alimentos, especialmente frutas. OBJETIVO: Avaliar a freqüência de sensibilização ao látex e a frutas em profissionais da área da saúde. MÉTODOS: Foram avaliados 53 profissionais da saúde, 81,9% do sexo feminino, aplicando-se questionário alergológico e testes cutâneos por puntura para alérgenos inaláveis, do látex e de frutas (mamão papaia, kiwi, abacate, banana, figo, tomate, noz). RESULTADOS: Dos 53 indivíduos estudados, 15 (28,5%) eram alérgicos ao látex. A sensibilidade a frutas foi diagnosticada em 14 (26,4%), dos quais 10 (18,8%) apresentavam teste por puntura positivo para o látex; as frutas alergênicas mais freqüentes foram papaia (80,0%), kiwi (60,0%) e abacate (50,0%). CONCLUSÃO: Estes achados demonstram a existência da alergia látex-fruta, como descrito na literatura, sendo de suma importância uma avaliação in vivo em profissionais da área de saúde, caracterizados como potencial grupo de risco.

Allergens and natural rubber proteins

BACKGROUND

Allergy to natural rubber latex (NRL) results from exposure to proteins derived from Hevea brasiliensis. Type I latex hypersensitivity is observed in certain occupational and other high-risk groups with frequent exposure to NRL products. This includes health care workers (HCWs), workers in the latex industry, children with spina bifida, and atopic individuals.

OBJECTIVES

Early reliable diagnosis and avoidance are required for better patient care. Standardized reagents are not presently available for in vitro and in vivo testing and treatment of patients with latex allergy. However, a number of allergens have been isolated and characterized from Hevea latex and NRL products. Currently, a total of 11 major and minor allergens are designated by the International Allergen Nomenclature Committee. This article reviews the structural and functional characteristics of these latex allergenic proteins.

RESULTS

NRL-allergenic proteins include those involved in the biosynthesis of polyisoprene and coagulation of latex rubber elongation factor, small rubber particle protein, prohevein, and patatin. Pathogenesis-related proteins include beta-1,3-glucanases, chitinases, and hevamine; and the structural proteins include microhelix protein complex, proline-rich protein, profilins, enolases, and manganese superoxide dismutase. Recombinant allergens demonstrated skin test reactivity in patients with latex allergy. The minimal level of skin test reactivity was about 70 pg/mL for NRL and 1 ng/mL for recombinant allergens. The use of selected recombinant latex allergens (Hev b 5, Hev b 6, and Hev b 7) in skin prick tests identified 93% of allergic individuals, mainly health care workers.

CONCLUSIONS

Recombinant latex allergens are clinically reactive and can be produced in a standardized manner, which could potentially provide safe and sensitive reagents for the diagnosis and treatment of type I latex allergy.

Latex allergy: prevalence, risk factors, and cross-reactivity

There are few little exact epidemiological data on the prevalence and incidence of latex allergy, partly because the diagnostic tools are unsatisfactory and partly because the epidemiological study planning often does not fulfill criteria of good praxis. On the basis of present data, latex allergy in normal population is low, under 1%. Known risk groups such as health care workers, atopic subjects, people with hand dermatitis, and especially spina bifida patients show higher prevalence numbers. The common serological cross-reactivity between latex and a great number of different fruits and vegetables is bound to common plant pathogenesis-related proteins and storage proteins. Despite positive serological tests, only about half of NRL-allergic subjects have clinical symptoms after eating cross-reacting foods.

Latex hypersensitivity: personal data and review of the literature

Latex allergy is an increasingly common condition, because use of latex products is widespread. The reactions to latex manufactures can be classified as allergic and non-allergic, these are the most common. Latex proteins are responsible for immediate IgE-mediated hypersensitivity allergic reactions. Symptoms range from rhinitis, conjunctivitis and urticaria to anaphylactic shock. Chemical additives can cause allergic contact dermatitis. The clinical symptoms of latex allergy could arise from direct contact with latex products, but may also result from inhalation of airborne allergens. Subpopulations at particular risk include: atopics, children with spina bifida or individuals who required frequent surgical instrumentations, health care workers, and all persons who have regular contact with latex products. Diagnosis of allergy is based initially on history: search for specific serum IgE, skin prick test and provocation test may confirm the suspicion. The most effective strategy in the treatment of latex allergy is avoidance, however this is virtually impossible, given large number of latex products we encounter since childhood. In this paper we review the current state of knowledge concerning latex allergy, including the clinical spectrum, identified allergens, the cross-reactions regarding the latex-fruit syndrome, diagnostic procedures and preventive measures. Several personal data increase awareness on this issue.

Alergia látex-fruta

O látex está sendo considerado o alergênico do ano 2000, tendo em vista que inúmeros indivíduos, principalmente profissionais da área de saúde e pacientes submetidos a várias intervenções diagnósticas e terapêuticas, estão freqüentemente expostos aos alérgenos do látex, presentes em produtos de borracha natural. As manifestações clínicas conseqüentes às reações alérgicas de hipersensibilidade imediata vão desde rinite, urticária, conjuntivite, angioedema, asma, até anafilaxia. Estudos recentes estão demonstrando que pacientes alérgicos ao látex desenvolvem concomitantemente sensibilização a certos alimentos de origem vegetal, especialmente frutas como papaia, figo, banana, abacate, kiwi, pêssego, abacaxi, melão e castanha, acreditando-se numa provável ocorrência de reações cruzadas entre os alérgenos do látex e destas frutas. Faz-se, então, uma revisão sobre a alergia ao látex, em particular sobre os grupos de risco, incluindo a presença de reatividade cruzada entre o látex e as frutas.

Digestibility of allergens extracted from natural rubber latex and vegetable foods

BACKGROUND

Several cross-reactive allergens are now known to be involved in the defense responses of higher plants. Such proteins are drawing the attention of plant breeders because of their antimicrobial or stress-alleviating activities. Plants genetically modified to express defense-related proteins are being developed. The current concern is focused on the allergenicity of these intentionally expressed proteins.

OBJECTIVE

It is believed that food allergens are proteins resistant to digestion. Digestibility tests have been accepted as an appropriate method for evaluating the allergenicity of newly introduced proteins. In this study we investigated the usefulness of this method for detecting allergens from natural rubber latex and vegetable foods.

METHODS

Proteins were extracted from rubber latex, potato, and 5 kinds of fruits. Simulated gastric fluid (SGF) and simulated intestinal fluid (SIF) were used for the digestibility test. An aliquot of each digest was periodically withdrawn and analyzed. Allergens were detected with pooled sera from individuals with latex allergy or patients given a diagnosis of oral allergy syndrome.

RESULTS

Most latex and vegetable food proteins were digested by the SGF within 4 minutes. Numerous allergens were also decomposed by the SGF within 8 minutes. Although vegetable food allergens were relatively stable in the SIF, kiwi allergens were substantially degraded by the SIF within 16 hours.

CONCLUSION

The pronounced lability of the plant-derived allergens was thought to reflect the discrete sensitization and elicitation processes of patients with latex-fruit syndrome or oral allergy syndrome. These results indicate that the allergenicity of a newly expressed protein should be carefully evaluated according to not only its digestibility but also other important properties.

Health-care workers and latex allergy

Latex hypersensitivity can pose a threat to anyone, but health-care providers are among the high-risk groups for developing latex hypersensitivity. Latex hypersensitivity likely results from health-care workers' increased use of gloves following implementation of universal precautions. It is also believed that the antigenic load of latex gloves causes an increase in latex hypersensitivity resulting from massive production of gloves. Although there are many studies on the prevalence of latex hypersensitivity among health-care workers, there appear to be discrepancies, which may affect the different apparent prevalence. Testing for latex hypersensitivity raises another problem. Latex allergens cannot be identified specifically; therefore, there is no standard test or testing solution that can identify hypersensitive persons. Although latex glove hypersensitivity was first identified in the late 1970s, there remain many uncertainties associated with it; as a result, there is a growing concern among health-care providers. The authors offer several precautions to avoid the development of latex hypersensitivity.

Latex allergy

Latex allergy continues to be an important medical problem. In this review we re-examine the definition of latex allergy, the offending allergens, the factors that enhance sensitization, the threshold levels that sensitize and elicit reactions in sensitized individuals, current diagnostic techniques, avoidance measures, the barrier properties of nonlatex alternatives, and the roles of premedication and immunotherapy. Twenty years after its resurgence, latex allergy is a well-defined condition with established diagnostic criteria and rational treatment and prevention strategies. However, in spite of advances associated with molecular studies of latex allergens and improved understanding of immunotherapy, avoidance remains the only effective treatment.

Cross-reactions in the latex-fruit syndrome: A relevant role of chitinases but not of complex asparagine-linked glycans

BACKGROUND

Cross-reactions between latex and plant foods (mainly fruits) have been widely reported. Although the cross-reactive components have not been well identified, class I chitinases seem to be the most credible candidates in chestnut, avocado, and banana.

OBJECTIVE

We sought to evaluate the potential role of chitinases and complex glycans as cross-reactive determinants linked to latex-food allergy.

METHODS

Extracts from 20 different plant foods and from latex were obtained. These preparations were immunodetected with anticomplex glycans and antichitinase sera raised in rabbits, as well as with sera from patients with latex-fruit allergy and sera from patients allergic to latex without food allergy. Immunoblot inhibition assays were carried out by using a purified class I chitinase from avocado or latex extract as inhibitors.

RESULTS

Reactive proteins of approximately 30 to 45 kd (putative class I chitinases) were recognized by both specific polyclonal antibodies to chitinases and sera from patients with latex-fruit allergy in chestnut, cherimoya, passion fruit, kiwi, papaya, mango, tomato, and flour wheat extracts. Prs a 1, the major allergen and class I chitinase from avocado, and the latex extract strongly or fully inhibited IgE binding by these components when tested in immunoblot inhibition assays. Additional bands of 16 to 20 kd, 23 to 28 kd, and 50 to 70 kd were detected by the antichitinase serum but not with the patients' pooled sera. The putative 30- to 45-kd chitinases present in different food extracts did not react with a pool of sera from subjects allergic to latex but not to fruit. Very different immunodetection patterns were produced with the anticomplex glycan serum and the sera from allergic patients.

CONCLUSIONS

Putative class I chitinases seem to be relevant cross-reactive components in foods associated with the latex-fruit syndrome, but do not play a specific role in allergy to latex but not to fruit. Cross-reactive carbohydrate determinants are not important structures in the context of latex-fruit cross-sensitization.

Latex: a cause of allergic contact eczema in users of natural rubber gloves

BACKGROUND

Latex is a common cause of contact urticaria in glove users. We recently found that 1.2% of patients attending a contact dermatitis investigation unit had delayed type hypersensitivity to latex as a cause of eczema.

OBJECTIVE

We reassessed the relevant contact allergens in users of natural rubber gloves with hand dermatitis. Particular emphasis was placed on allergens not included in the standard patch test series.

METHODS

Consecutive natural rubber glove users with hand dermatitis were investigated for the presence of contact dermatitis and urticaria.

RESULTS

One hundred seventeen consecutive patients were tested. The American standard series missed 34% and the European 40% of patients with positive patch test reactions to rubber related chemicals. Six percent of patients (20% of those with a positive reaction) demonstrated delayed type hypersensitivity to latex, often in the absence of other relevant contact allergens and contact urticaria to latex.

CONCLUSION

Latex is a relatively common cause of allergic contact eczema in the absence of contact urticaria. Latex should be included in a rubber series for screening patients with hand dermatitis who are glove users.

Class I chitinases with hevein-like domain, but not class II enzymes, are relevant chestnut and avocado allergens

BACKGROUND

Several foods associated with the latex-fruit syndrome present relevant allergens of around 30 kd. Neither these components nor any other responsible for the reported cross-reactions have been identified and purified.

OBJECTIVE

We sought to isolate and characterize the 30 kd allergens from avocado fruit and chestnut seed, two of the main allergenic foods linked with latex allergy.

METHODS

Sera from patients allergic to chestnut and avocado were selected according to clinical symptoms, specific IgE levels, and positive skin prick test responses. Class I and II chitinases were purified by affinity and cation-exchange chromatography and characterized by specific IgE and anti-chitinase immunodetection, immunoblot inhibition assays, enzymatic activity tests, and N-terminal sequencing.

RESULTS

Relevant 32 kd allergens were detected by specific IgE immunodetection in both avocado and chestnut crude extracts. The same bands, together with others of 25 kd, were revealed by a monospecific antiserum against class II chitinases. Purification and characterization of the 32 kd allergens from both plant sources allowed their identification as class I chitinases with an N-terminal hevein-domain. The purified allergens fully inhibited IgE binding by the corresponding crude extract when tested in immunoblot inhibition assays. Highly related 25 kd class II chitinases that lack the hevein-like domain were also isolated from the same protein preparations. No IgE-binding capacity was shown by these class II enzymes.

CONCLUSION

Class I chitinases are relevant allergens of avocado and chestnut and could be the panallergens responsible for the latex-fruit syndrome. The hevein-like domain seems to be involved in their allergenic reactivity.

Cloning and characterization of a latex allergen (Hev b 7): homology to patatin, a plant PLA2

We previously identified a 46-kD protein allergen in latex as having amino acid sequence homology to the patatin gene family. The objective of this study was to characterize this protein by molecular techniques. RNA was isolated from the latex or leaf material from Hevea brasiliensis and from potato tubers. Specific polymerase chain reaction (PCR) primers were designed from the amino acid sequence and reverse transcriptase (RT)-PCR amplified a specific product from latex RNA that was subsequently cloned and sequenced. This product was 1493 bp in length with an 1167 bp open reading frame. The deduced amino acid sequence encodes for a 389 aa protein, pI 4.82 with 43% homology to tobacco patatin. Northern analysis of potato, Hevea leaf, and latex RNA demonstrated the message to be most abundant in latex, weakly present in Hevea leaf, but no hybridization occurred with potato RNA. Patatin has lipid acyl-transferase and PLA2-like activity, suggesting it plays a role as a defence-related protein. Other defence-related proteins in latex such as hevein, glucanase, and hevamine are also allergens. Increased production of defence-related proteins as a result of increased tapping of the rubber trees to meet the demand for latex may explain the increased allergenicity of latex.

Asthma caused by Ficus benjamina latex: evidence of cross-reactivity with fig fruit and papain

BACKGROUND

Ficus benjamina or weeping fig is a plant used increasingly for indoor decoration that can cause allergic rhinitis and asthma.

OBJECTIVE

We report a clinical and immunologic study in a patient with perennial asthma caused by F. benjamina latex in whom several episodes of angioedema of the oropharyngeal tract and tongue followed ingestion of figs and kiwi.

METHODS

Hypersensitivity to latex from F. benjamina and from Hevea brasiliensis, fig fruit, kiwi, papain, and bromelain was investigated by means of skin prick test, specific IgE determination by CAP, histamine release test, and bronchial provocation test to F. benjamina latex. CAP-inhibition assays were carried out to study possible cross-reactivity among these antigens.

RESULTS

Hypersensitivity to F. benjamina latex, fig, kiwi, and proteases was demonstrated by means of skin prick test, determination of specific IgE and histamine release test. Bronchial provocation test with F. benjamina latex resulted in a dual asthmatic reaction, confirming the etiologic role of this plant. A rise of eosinophil cationic protein in patient's serum was observed 21 hours after bronchial challenge, suggesting activation of eosinophils. Inhibition assays showed that F. benjamina latex as liquid-phase inhibited up to 95% the CAP to fig and up to 57% the CAP to papain. Neither sensitization nor cross-allergenicity with H. brasiliensis latex was found.

CONCLUSIONS

Hypersensitivity to F. benjamina latex may cause IgE-mediated respiratory allergy. The association with allergy to fig and papain is likely due to the existence of cross-reactive allergen structures.

Endotoxin as a factor in adverse reactions to latex gloves

BACKGROUND

Endotoxin is an inflammatory made by gram negative bacteria that can irritate the skin, induce respiratory problems, fever, and shock. It is an adjuvant for both delayed hypersensitivity and IgE production and has been shown to magnify antigen specific mediator release. Since many of the clinical problems associated with natural latex products involve similar clinical sequelae, we investigated the possibility that latex gloves might be contaminated with endotoxin.

OBJECTIVE

To measure the endotoxin content of a variety of natural latex gloves, investigate the its distribution and origin, associated with latex proteins, and determine the particle sizes associated with its release.

METHODS

Endotoxin, protein, and allergen were measured using a quantitative kinetic Limulus assay, modified Lowry, and RAST inhibition, respectively. Particle size and density were determined using an Anderson multistage air sampler and CsCl2 gradient.

RESULTS

Endotoxin was found to be a highly significant contaminant of some latex gloves. Levels ranged from 0.09 ng to 2.8 micrograms/g of glove. Protein levels ranged from < 25 to 1150 micrograms/g of glove while allergen levels ranged from < 1 to 837 micrograms/g of glove. Endotoxin and protein eluted rapidly from the interior of the gloves tested. Greater than 70% of the endotoxin was found to be associated with particles in the < 7 microns aerodynamic diameter range. The highest levels of endotoxin were found in nonsterile examination gloves with a tendency towards powdered gloves containing more endotoxin and protein. A slurry containing cross-linked dextran through which gloves were dipped revealed very high endotoxin contamination (64 micrograms/mL) while unused cross-linked dextran has very little associated endotoxin.

CONCLUSIONS

These data demonstrate that some natural rubber latex gloves, particularly nonsterile examination gloves, are contaminated with high amounts of endotoxin and proteins. These were found mostly on the inside of gloves and were released as very small respirable particles that were not physically associated with the powder. These findings support the hypothesis that endotoxin may be responsible for some of the tissue irritation associated with latex glove use. In addition, this material may be responsible for the enhancement of delayed and immediate hypersensitivity reactions to chemicals and proteins found in these products and offers a possible explanation for the disproportionate severity of these reactions.

Natural latex, grass pollen, and weed pollen share IgE epitopes

BACKGROUND

Because of the frequent use of natural latex products, IgE-mediated reactions to latex proteins represent an important health threat in industrialized countries. Although several latex allergens have been characterized and IgE cross-reactivities with allergens present in plant-derived food have been described, limited information is available regarding the presence of common IgE-binding components in latex and plant pollen.

METHODS

By using serum IgE from 56 individuals with latex allergy, the IgE-binding components in ammoniated latex milk and latex glove extracts were characterized by immunoblotting. The presence of cross-reactive IgE-binding components in the different latex extracts, extracts from mugwort, ragweed, timothy grass pollen, and recombinant birch pollen allergens (Bet v 1 and Bet v 2 [birch profilin]) was studied by immunoblot inhibitions and quantitative competition experiments. The involvement of carbohydrates in the constitution of cross-reactive IgE epitopes was studied by periodate treatment of extracts.

RESULTS

Although sera from certain individuals with latex allergy showed IgE reactivity with protein bands of different molecular weights in Western-blotted latex milk and glove extracts, both extracts contained common IgE epitopes. Although preincubation with recombinant Bet v 1 and Bet v 2 did not significantly inhibit IgE binding to latex proteins, weed and, in particular, timothy grass pollen extract strongly inhibited IgE binding to latex allergens. The cross-reactive IgE epitopes were sensitive to periodate treatment.

CONCLUSIONS

Mugwort, ragweed, and timothy grass pollen share IgE epitopes with glycoprotein latex allergens. The presence of common epitopes might in part explain clinical symptoms in patients allergic to pollen on contact with latex.