Latex-specific IgE Antibodies Research Articles

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.

Immunological Analysis of the Alternate Rubber Crop Taraxacum koksaghyz Indicates Multiple Proteins Cross-Reactive with Hevea brasiliensis Latex Allergens

The public health risk of Type I natural rubber latex allergy, caused by residual proteins in Hevea brasiliensis rubber latex (HNRL) products, has led to some medical examination and surgeon’s gloves and other health-related products being made from synthetic polymers. However, they are generally not preferred by healthcare providers due to their physical limitations. Guayule latex (GNRL), from an alternate rubber crop Parthenium argentatum, has been proven to contain none of the protein antigens present in H. brasiliensis natural rubber latex and its products. Guayule latex has also exhibited excellent film properties. Another alternate rubber crop, Taraxacum kok-saghyz, is now under commercial development, and internet reports assume that, like guayule, its latex derived rubber is free of proteins that are cross-reactive with HNRL specific IgE antibodies. Thus, the assumption is that it will not trigger allergic reactions in Type I HNR latex allergic individuals. Using ELISA and immunoblot methods, we have tested the reactivity of HNRL protein specific murine monoclonal and polyclonal antibodies, rabbit polyclonal IgG antibodies and human IgE antibodies from clinically HNRL allergic individuals against T. kok-saghyz latex and its purified rubber particles. We demonstrate that T. kok-saghyz latex contains multiple HNRL cross-reactive proteins, which importantly react with HNRL latex specific human IgE antibodies from Type I latex allergic individuals. Exposure of HNRL allergic individuals to T. kok-saghyz latex may thus place them at risk for allergic reactions.

Exposure testing with powdered gloves in 60 health care workers with latex allergy

Type 1 sensitization to natural rubber latex occurs in up to 22% of health care workers. Most sensitizations are due to the use of powdered latex gloves. Work place-associated exposure tests were performed to ascertain how frequently persons who developed breathing difficulties, rhinitis/conjunctivitis or obstructive respiratory tract illness when using powdered latex gloves are allergic to latex. 60 persons (48 women and 12 men; mean age 29 +/- 7 years) with type 1 sensitization to natural rubber latex were studied. The past history was obtained through a questionnaire specially designed for those with latex allergy. Diagnostic measures included prick tests with different latex allergens, measuring the concentrations of total and latex-specific IgE and exposure trials, related to the work place, with powdered vinyl and latex gloves. The prick tests with various latex allergens produced significant skin reactions in 59 subjects, 58 had latex-specific IgE antibodies (0.47 kU/l- > 100 kU/l). Exposure tests with powdered latex gloves produced rhinitis in 55 and conjunctivitis in 38 persons, urticaria in 3 and cough in 19. Whole-body plethysmography demonstrated a significant rise in respiratory tract resistance in 13, a reduction in 1-second expiratory volume of at least 20% in 15. Abnormal values in both tests were noted in 8 subjects. The breathing difficulty reported by all subjects was in most cases due not to bronchial obstruction but to obstructed nasal breathing. In cases with breathing difficulty on exposure to latex gloves a latex allergy should be considered as the cause. Powdered latex gloves present a danger to health care personnel and should no longer be used.

Latex allergy: low prevalence of immunoglobulin E to highly purified proteins Hev b 2 and Hev b 13

Hevea brasiliensis (Hev b) 2 and Hev b 13 have recently been identified as major latex allergens by detecting specific IgE antibodies in >50% of sera from Hev b latex-allergic individuals. We assessed the prevalence rates for sensitization to extensively purified latex allergens in patients from three diverse geographical areas. Native Hev b 2, Hev b 5, Hev b 6.01 and Hev b 13 were purified by non-denaturating chromatography and were used in ELISAs to assess sera from 215 latex-allergic patients and 172 atopic non-sensitized controls from Finland, Spain and the United States to detect allergen-specific IgE antibodies. Unexpectedly, even highly purified Hev b 13 contained epitope(s) to which Hev b 6-specific human IgE antibodies bound effectively. Further purification, however, reduced the prevalence of IgE antibody reactivity to low levels: 15%, 5% and 11% for Hev b 2, and 18%, 30% and 27% for Hev b 13 among latex-allergic Finnish, Spanish and American patients, respectively. Interestingly, Finnish patients had a lower prevalence of Hev b 5-specific IgE antibody (28%) as compared with Spanish (49%) and American (71%) patients. The prevalence of Hev b 6.01-specific IgE reactivity was uniformly >50% in all three populations. Neither Hev b 2 nor Hev b 13 appear to be major latex allergens when evaluated in serological assays using highly purified allergens. The reason(s) for the observed differences in published sensitization rates in various geographic regions requires further study. The purity of the allergen preparations has a marked impact on the accuracy of latex-specific IgE antibody detection in epidemiological studies and in the serological diagnosis of latex allergy.

Latex allergy in healthcare workers: An epidemiological study in a Spanish hospital

To design an effective prevention program in health care workers who are allergic to latex it is necessary to know the current epidemiological situation. The objectives were to determine the main factors associated with latex allergy and to quantify levels of airborne latex particles in different areas of our hospital. A cross-sectional study was conducted using a questionnaire completed by health care workers. Those who answered the first questionnaire were given a second one to fill out and an allergological study (skin-prick test and latex-specific IgE antibodies) was performed. Latex aeroallergen particles were collected with a Quan-tec-air in different areas of the hospital. The first questionnaire was sent to 2551 health care workers. Eight hundred forty-one (33.14%) subjects returned the completed questionnaire and were given the second questionnaire. One hundred fifty-four completed second questionnaire. We identified 28 patients who were allergic to latex, and 126 patients who were not allergic to latex. In the allergic population there were more nurses aides. More allergic patients were found in the Surgery Department, Intensive Care Unit (ICU), and Vascular Radiology Unit (VRU). Allergic patients were more likely to use a higher number of latex gloves and during more hours than nonallergic workers. In the Surgery Department, ICU, VRU, and Laboratory Department more pairs of latex gloves were used and during more hours. The medium level of latex aeroallergens in 24 determinations in 14 areas of the hospital was 8.12 ng/m3 (SD, 13.32 ng/m3; range, 0.3-57.7 ng/m3). The higher levels were found in Laboratory (n = 2; mean (M) 23; SD, 25.95 ng/m3) and Surgery Departments (n = 11; M, 7.43; SD, 16.98 ng/m3; Kruskal Wallis test, p = 0.09). Latex allergy is an important health problem for health care workers, especially for those working in surgical areas or in those places where more latex gloves are used; in these areas higher levels of airborne latex particles are found. We should take into account these data to design an effective secondary prevention program.

Early exposure to latex products mediates latex sensitization in spina bifida but not in other diseases with comparable latex exposure rates

The high prevalence of latex sensitization in patients with spina bifida (SB) has been attributed to repeated and early exposure to latex products. Other diseases such as gastroschisis/omphalocoele and post-haemorrhagic/congenital hydrocephalus are also associated with repeated and early latex exposure. The aim of the study was to evaluate whether the high prevalence of latex sensitization in patients with SB is rather related to the underlying disease itself than to disease-associated known risk factors. We compared children with SB (n=35), children with gastroschisis/omphalocoele (G/O, n=20) and children with post-haemorrhagic/congenital hydrocephalus (PH, n=45). All children with SB and PH had a ventriculo-peritoneal shunt since a very young age. Patients who underwent three or less surgical procedures matched in terms of age, number of operations, atopy and gender distribution, and were analysed for IgE sensitization rates to latex. In the SB group, 16 of 35 patients (46%) showed elevated latex-specific IgE antibodies in contrast to one of 20 patients (5%) in the G/O group and four of 45 patients (8.9%) in the PH group (P<0.0005 and P<0.005, Fisher's exact test). Comparing matched control groups (<or=3 operations), the effects remained significant (P<0.05 and P<0.01). This study suggests that the SB population bears a disease-associated propensity for latex sensitization. This effect cannot be explained exclusively by a higher number of operations and differences related to atopy, age or gender.

Prevalence of latex-specific IgE antibody among the children with/without allergic disease in Japan

Rationale Latex allergy is frequently seen in high risk group: patients with spina bifida, medical and co-medical workers in surgical department and industry workers. Latex is also used in many things for the children, i.e., tennis ball, basket ball, cloths and some toys. But prevalence of latex-specific IgE antibody in children with or without allergy has not been well defined in Japan. Aim To know prevalence of Latex-specific IgE antibody among children with or without allergic diseases. Methods 768 children, 1 to 20 years old, the average age 5.7 years old; 291 subjects with the allergic disease (257 subjects with bronchial asthma, 184 subjects with atopic dermatitis, 92 subjects with food allergies, 184 subjects with allergic rhinitis and 56 subjects with allergic conjunctivitis) and 477 subjects without allergic diseases were examined. Latex-specific IgE antibody and other food-specific IgE antibodies were evaluated by using Parmacia CAP system. Results Latex-specific IgE antibody was positive in 16.1% patients with allergic diseases, only 4.8% were positive in non-allergic patients (p<0.01). Conclusions High prevalence of Latex-specific IgE antibody among children with allergic diseases was observed. One has to recognize Latex as a potent allergen for the allergic children, especially who are needed operative therapy and the children with cause-unknown wheezing.

Performance of methods for the measurement of natural rubber latex (NRL) proteins, antigens and allergens

Rationale Determination of natural rubber latex (NRL) allergenic proteins in medical and consumer products promotes rational selection of products to minimize sensitization. The objective of this multi-center study was to assess the variability and relative analytical performance of available laboratory methods to measure NRL proteins. Methods Extracts from powdered and powder-free latex medical gloves (n=30, 5ml PBS/G, agitation-2hr), were analyzed for total protein (ASTM D5712 Modified Lowry-4 labs), antigenic proteins using rabbit antisera (ASTM- D6499-2 labs; LEAP-1 lab), total allergens using latex-specific human IgE antibody (RAST/ELISA Inhibition Assays-6 labs) and for individual H. brasiliensis allergens Hev b 1,3,5,6.02 using monoclonal antibodies (FITkit-7 labs). Precision profile analysis evaluated intra- and inter-laboratory variability and inter-method comparability. Results The sum of the 4 Hev b allergen monoclonal assay values displayed the highest correlation with RAST/ELISA inhibition values for total allergen, which were considered most reflective of the extractable latex allergen content from gloves (r 2=0.91-0.95). The total protein levels as measured with ASTM D5712 Modified Lowry method showed the next best correlation with RAST/ELISA inhibition assay generated allergen content (r 2=0.79-0.85). While results of the LEAP and D6499 latex antigen assays correlated well with one another (r 2=0.92), they were less reflective of glove allergen content compared to RAST/ELISA inhibition assay results. Conclusions Good agreement between the combined Hev b 1,3,5,6.02 content and the allergen level as assessed by human IgE-based RAST/ELISA inhibition assays, suggests that that monoclonal antibody-based immuno-enzymetric assay analysis may be a useful indicator for the allergen content of NRL products.

Strategies for distinguishing asymptomatic latex sensitization from true occupational allergy or asthma

To evaluate strategies for distinguishing those individuals with true occupational asthma caused by exposure to natural rubber latex from those individuals with allergic disease related to other allergens. Article published between January 1, 1981, and December 31, 2001, were identified via a MEDLINE search with the following keywords: latex, allergy, asthma, occupation asthma, and adverse reactions. English-language reports concerning diagnostic methods in latex and other forms of occupational asthma. Many methods have been evaluated for the diagnosis of latex allergy, including medical history, skin prick tests, in vitro tests, and various challenge tests. Skin prick tests with well characterized latex extracts are highly sensitive and specific predictors of latex-specific IgE antibodies; however, direct pulmonary challenge with latex allergen appears to be the only highly reliable method for diagnosis of latex-related occupational asthma. It is difficult to optimally distinguish between occupational latex asthma and asymptomatic latex sensitization in a person with preexisting asthma using currently available techniques.

Occupational allergies caused by latex.

Allergy to natural rubber latex is an important cause of occupational allergy in healthcare workers. Disposable medical gloves are the major reservoir of latex allergens, particularly powdered gloves, in healthcare delivery settings. Diagnosis of latex allergy requires a history of exacerbation of cutaneous, respiratory, ocular, or systemic signs and symptoms after exposure to natural rubber latex products; and evidence of sensitization by patch testing, skin testing, measurement of latex-specific IgE antibodies, or challenge testing. Optimal management of latex allergy involves education concerning cross-reacting allergens, reduction of cutaneous or mucosal contact with dipped rubber products, and minimization of exposure to latex aeroallergens in work environments.

The prevalence of latex-specific IgE in patients presenting to an urban emergency department

<h2>Abstract</h2> A correction to this article appears on page 160 of the January 2003 issue. <b>Study objective:</b> Since the first report of immediate hypersensitivity to latex was documented in 1979, latex allergy has been increasingly recognized as a medical problem in patient populations. However, there are no data available regarding the seroprevalence of latex sensitization in patients presenting to the emergency department. The overall aim of this study was to determine the prevalence of latex IgE seropositivity (L-IgE) in ED patients. <b>Methods:</b> We measured latex-specific IgE antibodies among a convenience sample of 1,027 patients using the AlaSTAT assay. We also measured serum IgE antibodies specific for 12 common inhalant allergens using the AlaTOP Microplate Allergy Screen assay. Demographic data were collected. Two questions related to latex allergy were queried. Descriptive statistics are presented. Point estimates and 95% confidence intervals (CIs) were calculated for each seroprevalence test. Odds ratios (ORs) and 95% CIs were used to assess the relationship between sex, race, and seropositivity to inhalant allergens and L-IgE. <b>Results:</b> The participation rate was 90% (1,027). The mean age of the patients was 46.9 years, 47.6% (489) were male, and 13.9% (143) were white. Eighty-four (8.2%; 95% CI 6.5% to 10.0%) had positive L-IgE results, and 23.8% (20) of patients with positive L-IgE results were classified as having strongly positive results. Bivariate analyses showed that being nonwhite (OR 4.7; 95% CI 1.5 to 15.1) and being seropositive for inhalant allergens (OR 7.4; 95% CI 4.2 to 13.1) were associated with L-IgE. <b>Conclusion:</b> The prevalence of latex sensitization in our sampling is substantial and higher than previously estimated in the general adult population. The clinical significance of seropositivity requires further evaluation. [<i>Ann Emerg Med.</i> 2002;40:411-419.]

The prevalence of latex-specific IgE in patients presenting to an urban emergency department

A correction to this article appears on page 160 of the January 2003 issue.Study objective: Since the first report of immediate hypersensitivity to latex was documented in 1979, latex allergy has been increasingly recognized as a medical problem in patient populations. However, there are no data available regarding the seroprevalence of latex sensitization in patients presenting to the emergency department. The overall aim of this study was to determine the prevalence of latex IgE seropositivity (L-IgE) in ED patients. Methods: We measured latex-specific IgE antibodies among a convenience sample of 1,027 patients using the AlaSTAT assay. We also measured serum IgE antibodies specific for 12 common inhalant allergens using the AlaTOP Microplate Allergy Screen assay. Demographic data were collected. Two questions related to latex allergy were queried. Descriptive statistics are presented. Point estimates and 95% confidence intervals (CIs) were calculated for each seroprevalence test. Odds ratios (ORs) and 95% CIs were used to assess the relationship between sex, race, and seropositivity to inhalant allergens and L-IgE. Results: The participation rate was 90% (1,027). The mean age of the patients was 46.9 years, 47.6% (489) were male, and 13.9% (143) were white. Eighty-four (8.2%; 95% CI 6.5% to 10.0%) had positive L-IgE results, and 23.8% (20) of patients with positive L-IgE results were classified as having strongly positive results. Bivariate analyses showed that being nonwhite (OR 4.7; 95% CI 1.5 to 15.1) and being seropositive for inhalant allergens (OR 7.4; 95% CI 4.2 to 13.1) were associated with L-IgE. Conclusion: The prevalence of latex sensitization in our sampling is substantial and higher than previously estimated in the general adult population. The clinical significance of seropositivity requires further evaluation. [Ann Emerg Med. 2002;40:411-419.]

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.

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.

Cross-Reactivity Studies of Gutta-Percha, Gutta-Balata, and Natural Rubber Latex ( Hevea brasiliensis)

Gutta-percha and gutta-balata are derived from the Paliquium gutta and Mimusops globsa trees, respectively, that are in the same botanical family as the rubber tree Hevea brasiliensis. For this reason the potential for immunological cross-reactivity between the gutta-percha and gutta-balata used in endodontics and natural rubber latex (NRL) has been the subject of some controversy, because these products may be used in latex-allergic individuals. The objective of this study was to investigate the potential cross-reactivity between gutta-percha, gutta-balata, and NRL. Physiological extracts of seven commercially available gutta-percha products, raw gutta-percha, raw gutta-balata, and synthetic transpolyisoprene were each analyzed for cross-reactivity with NRL in a competitive radioallergosorbent test inhibition assay. No detectable cross-reactivity was observed with any of the raw or clinically used gutta-percha products. In contrast the raw gutta-balata released proteins that were cross-reactive with Hevea latex. We conclude that the absence of gutta-percha proteins that can react with Hevea latex-specific IgE antibody supports the minimal potential for commercially available gutta-percha to induce allergic symptoms in individuals sensitized to NRL. Because gutta-balata is sometimes added to commercial gutta-percha products caution should be exercised if products containing gutta-balata are used in endodontic care of latex-allergic individuals.

Comprehensive analysis of 28 patients with latex allergy and prevalence of latex sensitization among hospital personnel.

Recently anaphylactic shock caused by latex gloves and medical instruments has been discussed as an important problem in surgical operations. Patients with contact urticaria or anaphylaxis due to natural rubber latex were first reported in Japan in 1993, and the number of cases is gradually increasing. In the present study, we analyzed 28 patients examined in our clinic from 1993 to 1998. The diagnosis of latex allergy was made on the basis of clinical history, latex specific IgE antibody, skin test, and use test. The 3 male and 25 female patients included 20 nurses, 4 doctors, 2 housewives, one animal hospital employee, and one worker in a senile rehabilitation center. The majority were health care workers. Contact urticaria from rubber gloves was the most common clinical symptom. Some of the patients developed severe attacks of anaphylaxis. During the period from 1995 to 1997, we also performed a questionnaire study and a serum examination of latex specific IgE antibody among the personnel of our university hospital. The screening test for the antibody was more reliable than our questionnaire study in detecting latex-sensitive persons. The prevalence of latex allergy was found to be 4.6%. This indicates that not only dermatologists but also all hospital workers should be aware of this type of allergy.

A blinded, multi-center evaluation of two commercial in vitro tests for latex-specific IgE antibodies.

To compare the diagnostic value of two commercial in vitro tests for the detection of latex-specific IgE antibodies. Serum samples were collected from latex-allergic and nonlatex-allergic individuals. Persons were classified as latex allergic if they had a positive clinical history and a positive skin prick test with a latex extract. Persons with no latex-related symptoms and negative skin tests were classified as nonlatex allergic. The serum samples were tested in a blinded fashion by a laboratory using the CAP (Pharmacia-Upjohn) and AlaSTAT (Diagnostic Products Company) assays. Values of 0.35 kA U/L or greater were considered positive in both tests. The 143 sera studied came from 83-latex allergic and 60 nonallergic persons. The in vitro tests were found to have sensitivities of 79.5% and 73.8%, and specificities of 90.2% and 91.7%, for CAP and AlaSTAT, respectively. The positive predictive values were 91.7% and 92.5%, while the negative predictive values were 76.4% and 71.4% for the CAP and AlaSTAT, respectively. In individuals classified by the combination of clinical history and skin test results, both the Pharmacia CAP and the DPC AlaSTAT demonstrated acceptable sensitivities, specificities, and predictive values for detection of antilatex IgE antibodies. These findings suggest that both assays can be useful adjuncts to the diagnosis of latex allergy.

249 The absence of Hev 5 in capture antigen may cause false-negative results in serologic assays for latex-specific IgE antibodies

249 The absence of Hev 5 in capture antigen may cause false-negative results in serologic assays for latex-specific IgE antibodies

Latex allergy in the workplace: an overview of where we are

INTRODUCTION Allergy to natural rubber latex has become the most common cause of occupational rhinoconjunctivitis and asthma among health care workers.1 In questionnaire-only surveys, up to 53% of responding health care workers2 self-report some type of reaction to rubber gloves. In surveys involving both questionnaires and either latex skin testing or immunoassays for latexspecific IgE antibodies, 5%3 to 17%4,5 of various hospital employee groups were documented as latex-sensitive. The high variation of prevalences reported is due to use of different skin test materials, small sample populations, and use of selected populations.

Natural rubber latex-specific IgE antibodies in non-healthcare workers: comparison of two FDA-clearedin vitro kits

Latex-specific IgE antibody immunoassays are heavily relied upon in the diagnosis of latex allergy in the United States. The goal of this study is to compare anti-latex IgE levels measured by two U.S. Food and Drug Administration (FDA)-cleared kits (CAP® System and AlaSTAT® Microplate) in sera obtained from employees in non-healthcare industries. Sera were obtained from 381 workers employed in several, non-healthcare industries over the past 10 years, and stored frozen. All 381 coded sera were analysed for latex-specific IgE using the Diagnostic Products Corporation microplate AlaSTAT® and the Pharmacia-UpJohn CAP® System. Concordance between methods and intra- and inter-assay reproducibility were evaluated. Twenty-six sera gave positive results using the AlaSTAT® assay (26/381, 6.82%), while 24 yielded CAP® positive results (6.30%). There were no significant differences (p = NS) between the assays' measurements of latex-specific IgE antibody levels for all 381 sera, yielding 0.28 ± 0.19 kU L−1 and 0.34 ± 0.59 kUA L−1, respectively. AlaSTAT® and CAP® assays agreed on the positive status of 9 (9/381, 2.4%) sera, and the negative status of 340 sera (340/381, 89.2%). The assays yielded discordant results on some individual sera. CAP® discordant results occurred in 17/26 sera (65.4%) of AlaSTAT® positive sera, while AlaSTAT® discordant results were found in 15/24 (57.7%) of the CAP® positive sera. The CAP® System, for instance, detected 0.39–2.3 kUA l−1 (1.03 ± 0.59, [mean ± SD]) of latex-specific IgE in the serum from 15 individuals that were all AlaSTAT® negative. In contrast, the AlaSTAT® detected 0.36–1.6 kU l−1 (0.62 ± 0.31, [mean ± SD]) of IgE anti-latex in the serum from 17 subjects that were all CAP® negative. These data indicate that the a priori seroprevalence of latex-specific sera IgE is about 6%–7% in non-healthcare workers and that the CAP® and AlaSTAT® assays agree on the positive or negative status of the majority of sera (91.6%). However, caution should be exercised when applying FDA-cleared in vitro assays for latex-specific sera IgE in populations known to have potentially low concentrations of latex-specific IgE antibodies, as there appears to be a finite possibility for these assays to misclassify sera as being positive or negative for latex-specific IgE antibodies. Published in 1999 by John Wiley & Sons, Ltd.