Skin test responses to latex in an allergy and asthma clinic

Opportunities and obstacles in translating evidence to policy in occupational asthma

PURPOSE

Occupational asthma (OA), a common respiratory disorder in Western countries, is caused by exposures at the workplace. It is part of a broader definition of work-related asthma (WRA) that also includes pre-existing asthma aggravated by substances present in the workplace environment, and it is potentially preventable. The purpose of this paper is to illustrate preventive measures for occupational asthma by case studies.

METHODS

In three case studies we discuss preventive measures that have been associated with reductions in incidence of occupational asthma from natural rubber latex and from diisocyanates as supported by published literature. We also discuss challenges in relation to asthma from cleaning products in healthcare work.

RESULTS AND CONCLUSIONS

Several preventive measures have been associated with reduction in incidence of occupational asthma from natural rubber latex and from diisocyanates, and may provide lessons for prevention of other causes of occupational asthma. Cleaning products remain an unresolved problem at present with respect to asthma risks but potential measures include the use of safer products and safer applications such as avoidance of spray products, use of occupational hygiene methods such as improving local ventilation, and when appropriate, the use of personal protective devices.

Ten years incidence of natural rubber latex sensitization and symptoms in a prospective cohort of health care workers using non-powdered latex gloves 2000-2009

OBJECTIVES

To assess the incidence of sensitization and gloves-related symptoms in 10-year follow-up in a group of health care workers (9,660 person-years) using non-powdered latex gloves from 2000 to 2009 and to examine related factors.

MATERIALS AND METHODS

We studied 2,053 health care workers in Trieste Hospitals by means of skin prick test for latex extract, patch tests and medical examinations. We report the incidence of latex sensitization among workers using non-powdered latex gloves.

RESULTS

The incidence of latex sensitization, rhinitis, asthma, urticaria, irritant and allergic contact dermatitis were 1.0; 0.12; 0.21; 0.72; 2.39 and 2.50 cases per 1,000 person-years, respectively. Respiratory symptoms and urticaria were positively related with latex sensitization (OR = 8.0; 95 % CL 1.27-48.6), with common allergic respiratory symptoms (OR = 4.19; 95 % CL 1.04-16.8) and with familial atopy (OR = 4.47; 95 % CL 1.1-17.9).

CONCLUSION

The incidence of latex sensitization and latex-related symptoms were very low but subjects with allergic symptoms related to common allergens are at higher risk. The use of non-latex gloves is suggested for them.

Prevention of latex allergy among health care workers and in the general population: latex protein content in devices commonly used in hospitals and general practice

BACKGROUND

In this study the latex protein content in devices commonly used in hospitals and general practice were investigated. The main aim was to acquire information for preventing latex allergy in health care workers and in the general population.

METHODS

About 22 different types of medical devices and 23 devices commonly used in general practice were examined evaluating the total allergenic potency by a modified RAST-inhibition assay and quantitative determination of single allergens (Hev b1, Hev b5 and Hev b6.02) by using commercial ELISA kit.

RESULTS

A high level of inhibition was found in medical devices, such as elastic bandage (81.57%), tourniquet (74.09%), Foley urinary catheter (68.35%), Penrose drainage (67.25%) and taping (39.6%), and in common devices, such as rubber inner-sole (84.20%), toy balloon (78.62%), latex mattress (74.27%), household rubber gloves (49.10%), working gloves (38.25%), inflatable floating mattress (32.10%). Concentrations of latex extractable proteins and Hev b1, Hev b5 and Hev b6.02 antigens were high in some medical and general devices.

CONCLUSIONS

Latex exposure sources were found in hospitals and the home. These findings, though only preliminary and far from conclusive, could enable sensitized persons to avoid risky exposures and prevent allergic reactions. From the point of view of prevention, the time may come when every natural rubber object could be systematically labelled as "containing latex" together with the warning that "this item may cause allergic reactions in sensitized subjects."

Latex allergy: a follow up study of 1040 healthcare workers

BACKGROUND

Natural rubber latex allergy can cause skin and respiratory symptoms The aim of this study was to evaluate the prevalence and incidence of latex related symptoms and sensitisation among a large group of healthcare workers in Trieste hospitals, followed for three years before and after the introduction of powder-free gloves with low latex release.

METHODS

In the years 1997-99 the authors evaluated 1040 healthcare workers exposed to latex allergen for latex related symptoms and sensitisation by means of a questionnaire, a medical examination, skin prick tests, and IgE specific antibody assay. The second evaluation was carried out in the years 2000-02, subsequent to the changeover to a powder-free environment.

RESULTS

Glove related symptoms were seen in 21.8% of the nurses (227), mostly consisting of mild dermatitis: 38 (3.6%) complaining of contact urticaria and 24 (2.3%) of asthma and/or rhinitis. These symptoms were significantly related to skin prick tests positive to latex (OR = 9.70; 95% CI 5.5 to 17) and to personal atopy (OR = 2.29; 95% CI 1.6 to 3.2). Follow up was completed in 960 subjects (92.3%): 19 new subjects (2.4%) complained of itching erythema when using gloves, but none was prick positive to latex. Symptoms significantly improved and in most cases disappeared (p<0.0001).

CONCLUSIONS

Simple measures such as the avoidance of unnecessary glove use, the use of non-powdered latex gloves by all workers, and use of non-latex gloves by sensitised subjects can stop the progression of latex symptoms and can avoid new cases of sensitisation.

Prevalencia de sensibilización al látex en personal sanitario

BACKGROUND AND OBJECTIVE

Latex exposure at work has been related to sensitization in health care workers. The aim of the present study was to determine the prevalence of this sensitization in health care workers and its risk factors.

PATIENTS AND METHOD

The occupation, prevalence of latex-related symptoms and sensitization was determined in a sample of health care workers by questionnaire and skin testing.

RESULTS

461 subjects were studied during a year. 30.2% of them reported dermatitis symptoms, 23.2% rhinitis, 12.6% urticaria-like rashes, and 5.6% reported asthmatic symptoms. 17.6% of workers reported symptoms when using latex gloves and 5% after the contact or ingestion of tropical fruits. Sensitization to latex was indentified in 12 workers (2.6%, CI95% 1.2-4.0). Dermatitis, urticaria-like rashes, rhinitis and asthmatic symptoms upon exposure to latex products and/or tropical fruits were all significantly more prevalent in sensitized subjects. In the logistic regression analysis, dermatitis, urticaria-like rashes, and asthmatic symptoms after the ingestion of tropical fruits were related to latex sensitization.

CONCLUSIONS

The prevalence of sensitization to latex in health workers is nearly 3% and it must be suspected in subjects reporting symptoms when using latex gloves or after the ingestion of tropical fruits.

Prevalence of skin test reactions to natural rubber latex in hospital personnel in Russia and eastern Europe

BACKGROUND

Allergic reactions to natural rubber latex have increased during the past 10 years, especially in many health care workers (HCWs) who have high exposure to latex allergens. The prevalence of skin test reactions to natural rubber latex in Russia, the Commonwealth of Independent States (CIS), and eastern Europe is unknown.

OBJECTIVE

The purpose of this study was to determine the prevalence of skin test reactivity to natural rubber latex in a population of HCWs exposed to latex.

METHODS

Nine hundred one HCWs regularly exposed to latex were evaluated using an allergy history questionnaire. Subjects were tested for latex allergy by titrated skin prick test with a biologically standardized latex extract. The diagnosis of latex allergy was defined by the presence of clinical symptoms when exposed to latex along with a positive skin prick test to latex.

RESULTS

Forty-nine (5.4%) HCWs were skin test-positive to latex. Seventeen (1.9%) HCWs were classified as latex-allergic based upon positive skin tests to latex associated with allergy symptoms with exposure. Seven of 901 HCWs had experienced anaphylactic reactions to latex. The most frequently reported symptom related to latex exposure was contact urticaria.

CONCLUSIONS

The prevalence of latex allergy among HCWs in Russia, the CIS, and adjacent eastern European countries is considerably less than reported in HCWs exposed to latex in western Europe and the United States. The low prevalence of latex allergy in Russia and the CIS suggests that lessened exposure to natural latex powdered gloves may diminish the prevalence of latex sensitization in HCWs in Russia and the CIS.

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

The accurate diagnosis of hypersensitivity to natural rubber latex is the initial step in the effective management of individuals with latex allergy and in ensuring the quality of epidemiologic studies. The diagnostic algorithm used in the evaluation of an individual with suspected latex allergy begins with a comprehensive clinical history during which risk factors (atopy, food allergies, hand dermatitis) and temporal relationships between symptoms and natural rubber product exposure are identified. If type IV hypersensitivity is suspected because of the delayed nature (hours to days) and confinement of symptoms to the skin-latex product contact areas, patch testing can be conducted to confirm the presence of activated T cells with specificity for rubber chemicals. If type I hypersensitivity is suspected because of ocular, upper and lower airway, and/or systemic symptoms that have rapid onset (minutes) after a definable latex exposure, a confirmatory skin or blood test for IgE antibody may be conducted to verify a state of sensitization within the individual. The definitive diagnosis would then be made only after consideration of the individual's clinical history and confirmatory in vivo and/or in vitro laboratory test results. If discordance remains between highly convincing latex-associated symptoms as identified in the history and repetitively negative confirmatory IgE antibody test results, then one of several types of in vivo provocation tests may be performed for adjudication. This overview examines the current state of the art in both in vivo and in vitro diagnostic methods for latex-specific IgE antibody detection in skin and blood. The performance, advantages, and limitations of each diagnostic method are compared.

Natural rubber latex allergy in the occupational setting

Over the last decade, the prevalence of natural rubber latex (NRL) allergy has reached epidemic proportions among workers who use or who are exposed to powdered latex products. NRL-associated occupational asthma is confined largely to those exposed to powdered latex glove use or other latex aerosols. The most frequent presenting symptom of NRL allergy is contact urticaria; inhalation may cause symptoms of allergic rhinitis and asthma. Skin prick testing is the most accurate tool for diagnosis of NRL allergy. The cornerstone of management is cessation of exposure; substitution with non-NRL or nonpowdered NRL gloves results in predictable rapid disappearance of latex aeroallergen.

Diagnosis of natural rubber latex allergy

The accurate diagnosis of a latex-allergic individual begins with a comprehensive clinical history. Atopy, food allergies, hand dermatitis, and temporal relationships between allergic symptoms and natural rubber product exposure are risk factors that increase the suspicion of latex allergy. If symptoms are temporally delayed (hours-days) and confined to skin-latex product contact areas, Type IV hypersensitivity should be suspected and patch testing may be performed to identify activated T cells that are specific for selected rubber chemical additives. If ocular, upper and lower airway, and/or systemic allergic symptoms are observed with rapid onset (minutes) following a definable latex exposure, Type I hypersensitivity should be suspected. One or several confirmatory tests for latex-specific IgE antibody in the skin or blood may next be performed to verify a sensitized (IgE antibody positive) state. If the clinical history remains discordant with a skin test or blood test result, in vivo provocation tests may be cautiously considered for adjudication. Diagnostic methods for latex-specific IgE antibody detection in skin and blood are overviewed, with a focus on their performance, advantages, and limitations.

Natural rubber latex allergy after 12 years: recommendations and perspectives

Natural rubber latex (NRL) allergy is a "new" illness whose prevalence reached epidemic proportions in highly exposed populations during the last decade. In children with spina bifida and in patients exposed to NRL during radiologic procedures, institution of prophylactic safety measures has had demonstrable effects in preventing allergic reactions. The risk of NRL allergy appears to be largely linked to occupational exposure, and NRL-associated occupational asthma is due almost solely to powdered latex glove use. Prevalence of NRL-allergic sensitization in the general population is quite low; several studies of young adults demonstrate rates of positive skin test results that are less than 1%. After occupational exposure, rates of sensitization and NRL-induced asthma rise dramatically in individuals using powdered NRL gloves but not in individuals using powder-free gloves. Airborne NRL is dependent on the use of powdered NRL gloves; conversion to non-NRL or nonpowdered NRL substitutes results in predictable rapid disappearance of detectable levels of aeroallergen. For these reasons, adoption of the following institutional policies designed to prevent new cases of NRL allergy and maximize safety is recommended: (1) NRL gloves should be used only as mandated by accepted Standard Precautions; (2) only nonpowdered, nonsterile NRL gloves should be used; and (3) nonpowdered, sterile NRL gloves are preferred for use. Low-protein powdered, sterile gloves may be used, but only in conjunction with an ongoing assessment for development of allergic reactions.

Risk factors for latex sensitization in children with spina bifida

BACKGROUND

Children with spina bifida represent the major risk group for latex sensitization.

PURPOSE

To determine the prevalence of latex sensitization in these children and to identify risk factors.

MATERIAL AND METHODS

We studied 57 patients with spina bifida. The mean age was 5.6 years and the male/female ratio was 0.8/1. In all patients a questionnaire, skin prick test (SPT) with latex (UCB-Stallergènes, Lofarma and ALK-Abelló), common aeroallergens and fruits (UCB-Stallergènes) and serum determination of total IgE (AlaSTAT) were performed.

RESULTS

The prevalence of latex sensitization was 30 %; only two sensitized children (12 %) had symptoms after exposure. Risk factors for latex sensitization were age >/= 5 years (p = 0.008; OR = 6.0; 95 % CI = 1.7-22.1), having at least four previous surgical interventions (p < 0.0001; OR = 18.5; 95 % CI = 3.6-94.8), having undergone surgery in the first 3 months of life (p = 0.008; OR = 5.4; 95 % CI = 0.7-29.2) and total serum IgE >/= 44 IU/ml (p = 0.03; OR = 3.8; 95 %CI = 1.1-13.1). Multiple logistic regression analysis showed that only a history of four or more surgical interventions (p < 0.0001; OR = 26.3; 95 %CI = 2.9-234.2) and total serum IgE >/= 44 IU/ml (p = 0.02; OR = 8.6; 95 % CI = 1.4-53.4) were independently associated with latex sensitization. Sex, family and personal allergic history, hydrocephalus with ventriculoperitoneal shunt, cystourethrograms, intermittent bladder catheterization and atopy were not related to latex sensitization.

CONCLUSIONS

In children with spina bifida, significant and independent risk factors identified for latex sensitization were multiple interventions and higher levels of total serum IgE. A prospective study will clarify the clinical evolution of assymptomatic children sensitized to latex.

Outcomes of a natural rubber latex control program in an Ontario teaching hospital

BACKGROUND

Allergy to natural rubber latex (NRL) has been frequently reported in health care workers. However, there is little published evidence of the outcome of hospital intervention programs to reduce exposure and detect cases of sensitization early.

OBJECTIVE

This study assesses the effects of intervention to reduce NRL allergy in an Ontario teaching hospital with approximately 8000 employees.

METHODS

A retrospective review assessed annual numbers of employees visiting the occupational health clinic, allergy clinic, or both for manifestations of NRL allergy compared with the timing of introduction of intervention strategies, such as worker education, voluntary medical surveillance, and hospital conversion to low-protein, powder-free NRL gloves.

RESULTS

The number of workers identified with NRL allergy rose annually, from 1 in 1988 to 6 in 1993. When worker education and voluntary medical surveillance were introduced in 1994, a further 25 workers were identified. Nonsterile gloves were changed to low-protein, powder-free NRL gloves in 1995: Diagnoses fell to 8 workers that year, and 2 of the 3 nurses who had been off work because of asthma-anaphylaxis were able to return to work with personal avoidance of NRL products. With a change to lower protein, powder-free NRL sterile gloves in 1997, allergy diagnoses fell to 3, and only 1 new case was identified subsequently up to May 1999. No increased glove costs were incurred as a result of consolidated glove purchases.

CONCLUSIONS

This program to reduce NRL allergy in employees was effectively achieved without additional glove costs while reducing expenses from time off work and workers' compensation claims.

[Latex allergy. Diagnosis and therapeutic aspects]

In the last two decades of the 20th century, latex allergy has reached epidemic proportions. Epidemiological studies demonstrate that 3-25 % of health personnel is allergic to latex. The main risk groups are health workers, machine operators in latex factories, and children with spina bifida and urogenital anomalies. From the allergenic point of view, latex contains 240 peptides but approximately 50 are able to react to IgE. Latex elongation factor Hevdl is the relevant allergen in patients with spina bifida. Prohevein (hev B6) behaves as a major allergen, since it reacts to IgE in most of the sera of patients with latex allergy. The nature of latex is complex; it is an allergenic mixture that depends on chemical, immunological and epidemiological variables. Latex proteins show strong cross reactivity with several proteins from fruit and vegetable grains such as avocado, potato, banana, tomato, chestnut, and kiwi. In vivo studies have shown that class I chitinase from avocado and chestnut behave as major allergens in allergic patients with latex-fruit syndrome. The clinical manifestations related to the use of latex products depend on the type of exposure, the amount of the allergen, and individual variability. The most useful diagnostic method is the skin prick test. Several perioperative guidelines are recommended in patients sensitized to latex as well as various alternatives to rubber gloves. An increasing number of studies describe the efficacy of etiological treatment (immunotherapy), using different guidelines and routes of administration. These preliminary data encourage the hope that in the near future immunomodulatory therapy will be available to mitigate against the latex allergy epidemic.

Natural rubber latex: glove use, sensitization, and airborne and latent dust concentrations at a Denver hospital

Exposure to natural rubber latex may cause immediate hypersensitivity reactions. Published latex sensitization prevalence rates range from 2.9% to 22% among health care workers, and from 0.12% to about 20% of occupationally unexposed populations. In this study, self-administered questionnaires addressed job and personal characteristics, glove use, and symptoms in two groups of hospital workers: those who regularly used latex gloves and those who did not. Serum was tested for latex-specific immunoglobulin E. Air, surface, and air-filter dust samples for natural rubber latex were collected. The prevalence of latex sensitization was 6.3% in the non-users and 6.1% in the latex glove users (P = 0.9); 81.3% of sensitized workers were atopic compared with 59.5% of non-sensitized workers (P < 0.05). Reporting of work-related hand dermatitis was more common in the latex glove users (23.4%) than in the non-users (4.9%), as were rhino-conjunctivitis (16.3% and 7.9%, respectively, [P < 0.01]), and hand urticaria (9.9% and 2.1%, respectively, [P < 0.01]). There was no significant difference in work-related symptoms between the sensitized and non-sensitized workers. Environmental concentrations of latex were higher in the work areas of the non-sensitized workers, but higher in the clinical than in the non-clinical areas. Occupational latex glove use was not a risk factor for sensitization.

Nasal provocation test in the diagnosis of natural rubber latex allergy

BACKGROUND

Natural rubber latex (NRL) allergy in workers using rubber gloves has been an occupational health problem for the last 10 years. In the case of the occupational agents, clinical history may be far from conclusive; hence, appropriate provocation should be carried out. The objective was to evaluate the usefulness of the nasal challenge test in the diagnosis of allergic rhinitis in subjects occupationally exposed to NRL.

METHODS

A single-blind, placebo-controlled study was conducted in 16 nurses with respiratory symptoms (bronchial asthma and/or rhinitis) related to NRL exposure as well as positive skin prick test (SPT) response to NRL. The controls were nine nurses with asthma and/or perennial rhinitis unrelated to NRL exposure; six atopic patients not occupationally exposed to NRL, with asthma and/or perennial rhinitis; and six healthy subjects. All the controls had negative results of SPT with NRL. Patients with a history of anaphylaxis or positive results of RAST to NRL were not considered in the study. The "nasal pool" technique was used to evaluate the cellular response and changes in protein level and ECP concentration in nasal washings after topical provocation with allergen or placebo.

RESULTS

A significant increase was noted in eosinophil and basophil number, albumin/total protein ratio, and ECP level only in NRL SPT-positive patients subjected to nasal challenge with NRL. Neither bronchial nor systemic reactions were found after the nasal provocation with NRL.

CONCLUSIONS

The nasal challenge test appears to be useful for diagnosing occupational rhinitis in NRL-sensitized patients.

Prevalence of latex sensitivity among patients with chronic renal failure: a new risk group?

Latex has been documented as causing immediate hypersensitivity reactions in forms ranging from contact urticaria to severe anaphylaxis. The prevalence of latex allergy appears to be higher in certain risk groups as a result of increased exposure or an increased intrinsic predilection for atopy. The purpose of the present study was to assess latex sensitivity in a large group of patients who are undergoing regular dialysis because of chronic renal failure (CRF) and to evaluate the relationship between latex sensitivity and skin prick test (SPT) responses to fruit allergens. Of the 268 patients tested, 3 subjects (1.1%) were found to have latex sensitivity via SPT. Although atopy was not demonstrated in any SPT positive subjects, there appears to be a considerable degree of crossreactivity between latex and certain fruit allergens which can be suggested as one subtext in the SPT positive patients. In conclusion, CRF patients with no history of hypersensitivity reactions should not be considered at risk for developing latex sensitization despite their frequent exposure.

Comparison of skin-prick test and specific serum IgE determination for the diagnosis of latex allergy

BACKGROUND

Latex IgE-mediated hypersensitivity has been recognized as an international health problem. However, there is poor information on the efficiency of the diagnostic methods available.

OBJECTIVE

The purpose of this study was to specify the efficiency of several diagnostic methods for latex allergy.

METHODS

We designed a prospective study involving 50 adult patients with latex allergy, as diagnosed by a suggestive clinical history and a positive skin-prick test (SPT) to a latex extract. One control group of 50 subjects paired for age, sex, total IgE levels and latex exposure, and another control group of 30 subjects with pollen allergy were used. A low-ammoniated natural-latex and several glove-latex extracts were elaborated. SPTs with these extracts, as well as with four different commercial-latex extracts were performed. Latex-specific serum IgE was determined by the CAP and the AlaSTAT methods.

RESULTS

Diagnostic sensitivity was 98% for the natural-latex extract SPT, from 90% to 98% for the commercial-latex extract SPT, and from 64% to 96% for the glove-latex extract SPT. Diagnostic specificity of SPT was 100%, and no severe adverse reactions were observed during skin testing. With respect to the latex-specific serum IgE determinations, sensitivity was 86% for the CAP system and 84% for the AlaSTAT assay, and specificity was dependent on the population considered.

CONCLUSION

SPT with natural latex extracts has shown a diagnostic efficiency close to 100%, significantly higher than that of latex-specific serum IgE determination.

Natural rubber-latex allergy in patients not intensely exposed

Immediate-type allergy to natural rubber latex (NRL) is common in highly exposed groups, particularly in health-care workers and patients with spina bifida. The occurrence of NRL allergy was investigated in subjects not belonging to such risk groups. A total of 493 patients presenting with various diseases for allergologic evaluation was studied. A questionnaire-based history was taken, skin prick tests with NRL milk and common aeroallergens were done, and NRL-specific serum IgE antibodies were measured. A total of 317 subjects (64.3%) was atopic. There were skin prick test reactions to NRL in 80 (16.2%) and NRL-specific IgE in the serum in 79 (16.0%) subjects; both were found in 25 patients (5.1%). Altogether, NRL sensitization was found in 134 patients (27.2%). By history and/or challenge tests, 13 subjects (2.6%) were diagnosed as having clinically relevant NRL allergy. In five of these, anaphylactic reactions had occurred during dental procedures, and in four during general anesthesia; 10 subjects reported immediate-type reactions to NRL products in daily life. All patients with clinically relevant NRL allergy had a skin prick test reaction to NRL milk (sensitivity 100%). Nine had specific IgE antibodies in the serum (sensitivity 69.2%); respective specificity was 86.0% or 85.4%. Nine of the 13 patients (69.2%) with NRL allergy were atopic. Despite exclusion of those at risk, many patients had clinically relevant allergy to NRL, and many of these had had severe reactions. NRL allergy is an important health issue also beyond the known risk groups.

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.

Occupational asthma due to latex in health care workers

Immediate hypersensitivity reactions ranging from mild urticaria to life threatening anaphylaxis after exposure to natural rubber latex have been reported frequently in health care workers while occupational asthma due to latex exposure is less well studied. The results of specific challenge tests and immunological tests in four health care workers with work related respiratory and skin disorders induced by the use of latex gloves are described. Occupational asthma was confirmed in three subjects by specific challenge tests. All had a positive skin test reaction to the latex extract; specific IgE antibodies were detected in only one subject. The fourth subject had a negative specific inhalation and skin test reaction to the latex extract. Peak expiratory flow monitoring at work and away from work showed a pattern consistent with work related asthma. These findings confirm that latex is a cause of occupational asthma in health care workers.

The relationship between latex skin prick test responses and clinical allergic responses

BACKGROUND

Allergic responses to latex have been reported more frequently in the past 5 years. Although commercial skin prick test solutions are available and can be used in the diagnosis of latex allergy in some countries, the characteristics of patients sensitized to latex relative to their skin test responses have not been reported.

OBJECTIVE

The purpose of this study is to relate the clinical characteristics of patients with latex sensitivity to the size of their latex skin prick test response.

METHODS

A retrospective review of patients who were attending a hospital-based allergy and asthma clinic and who had positive skin test responses to a commercial latex skin test solution was undertaken.

RESULTS

Of 47 patients who had skin test responses to latex, 36 had a mean wheal diameter at least 3 mm greater than the negative control (diluent). Sixty-eight percent were health care workers. There was a positive association between the size of skin test response and severity of latex-induced symptoms (p < 0.001). A history of banana sensitivity was also associated with larger skin test responses (p < 0.05).

CONCLUSION

The size of the skin prick test response to latex solution that is commercially available in Canada reflects the severity of latex-induced clinical allergic responses.

Sensitivity and allergy to latex in atopic and non-atopic children

To study the sensitivity and allergy to latex in children, we investigated sera of 306 atopic and 303 non-atopic children (median age 4.5 years) for specific IgE to latex. In patients with specific IgE to latex, a questionnaire was sent to families and provocation tests were carried out. 60/306 atopic children (20.8%) and 1/303 non-atopic children (0.3%) showed specific IgE to latex in serum. The proportion of atopic, latex-sensitized and provocation positive children was 12/48 (25%). Specific IgE to latex was significantly higher (p < 0.03) in symptomatic compared to non-symptomatic patients. Specificity of a positive history was 92%, sensitivity 50%. Atopic dermatitis tended to be more prevalent among the 12 provocation positive atopic children (75%) compared to 36 provocation negative children (58%). There was a tendency that children of the symptomatic group underwent surgical interventions more frequently compared to non-symptomatic children. In conclusion, latex sensitization and latex allergy seem to have occurred more often in atopic children than previously known. Risk factors for the development of a sensitization to latex are atopy and the clinical diagnosis of atopic dermatitis; risk factors for a clinically manifest allergy to latex are an elevated specific IgE to latex, a positive history upon contact to material containing latex and probably frequent operations. Provocation tests should be performed to plan avoidance measures in latex-allergic children especially before surgical interventions.