Natural Rubber Latex Extract Research Articles

Allergen component analysis as a tool in the diagnosis and management of occupational allergy

We are now in the epoch of “molecular allergology” and numerous clinically relevant allergenic molecules are available improving the performance of in vitro allergen tests and allergen detection methods. This review is focusing on characterized occupational allergens and their implementation into the in vitro diagnosis for occupational allergy and in allergen detection methods.More than 400 occupational agents are identified and documented as being ‘respiratory sensitizers’, but currently only a limited number of them are characterized on the molecular level and available for routine diagnosis as native or recombinant allergens. One exception, however, is natural rubber latex (NRL) from Hevea brasiliensis still remaining an important occupational allergen source. Characterization of 15 NRL allergens led to the development of assays for the determination of allergen content of NRL materials and the implementation of component-resolved diagnosis (CRD) for specific IgE antibody measurement. Microarray or singleplex using recombinant or native allergens are reliable tools for NRL allergy diagnosis. In addition, NRL allergy is an excellent model for improving extract-based specific IgE measurement by amplification of NRL extract preparation with stable recombinant major allergen rHev b 5. Despite the many efforts to characterize the occupationally relevant wheat allergens for baker’s asthma, the most frequently occurring forms of occupational asthma, the results are highly diverse. Wheat sensitization profiles of bakers showed great interindividual variability and no wheat allergen could be classified as the major allergen. For diagnosis of baker’s asthma, a whole wheat extract is still the best option for specific IgE determination. But single wheat allergens might help to discriminate between wheat-induced food allergy, grass pollen allergy and baker’s asthma. For workplace-related allergens like coffee, wood, soybean, seafood and moulds allergens are characterized and few of them are available, but their relevance for occupational sensitization routes should be verified in the further studies.

The role of allergen components for the diagnosis of latex-induced occupational asthma.

Recombinant Hevea brasiliensis (rHev b) natural rubber latex (NRL) allergen components have been developed to assess the patients' allergen sensitization profile and to improve the diagnosis of NRL allergy. To examine whether the determination of specific IgE (sIgE) reactivity to a panel of recombinant allergen components would be helpful for diagnosing NRL-induced occupational asthma (OA) in predicting the outcome of a specific inhalation test. sIgE levels to NRL extract and 12 recombinant NRL allergen components were assessed in 82 subjects with OA ascertained by a positive specific inhalation challenge (SIC) with NRL gloves and in 25 symptomatic subjects with a negative challenge. The sensitivity, specificity, positive predictive value, and negative predictive value of a NRL-sIgE level ≥0.35 kUA /l as compared to the result of SICs were 94%, 48%, 86%, and 71%, respectively. The positive predictive value increased above 95% when increasing the cutoff value to 5.41 kUA /l. Subjects with a positive SIC showed a significantly higher rate of sIgE reactivity to rHev b 5, 6.01, 6.02, and 11 than those with a negative SIC. A sIgE sum score against rHev b 5 plus 6.01/6.02 ≥ 1.46 kUA /l provided a positive predictive value >95% with a higher sensitivity (79%) and diagnostic efficiency (Youden index: 0.67) as compared with a NRL-sIgE ≥5.41 kUA /l (49% and 0.41, respectively). In suspected OA, high levels of sIgE against rHev b 5 combined with rHev b 6.01 or 6.02 are the most efficient predictors of a bronchial response to NRL.

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

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. 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. 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(®). 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.

Hev b 6.02 Is the Most Important Allergen in Health Care Workers Sensitized Occupationally by Natural Rubber Latex Gloves

Natural rubber latex (NRL) allergy is a common occupational disease in health care workers (HCW). However, few reports have compared the major allergen of HCWs to those in gloves that are routinely used in the hospital. The aim of this study was to evaluate the major NRL allergens in gloves used by HCWs. We studied 20 HCWs who were suspected to have latex allergy (LA). We performed a skin prick test (SPT) using NRL allergens. Serological testing was performed using the ImmunoCAPTM. The total amount of protein and the antigenic protein concentrations extracted from NRL gloves were measured. Four different types of FITkitTM were used to measure the concentrations of Hev b 1, 3, 5, and 6.02 in the gloves. A SPT using NRL extract identified 14 cases with positive reactions. The sensitivity and specificity of the SPT scores to the NRL glove extract were 100%. The sensitivity of latex specific IgE was 100% but the specificity was 14.2%. The sensitivity and specificity of rHev b 6.02 specific IgE were 100% in the LA group. The total amounts of protein from the medical gloves for surgery and examination were 265 microg/g and 95 microg/g, respectively. The antigenic protein concentrations in the gloves were 24.9 microg/g and 1.0 microg/g, respectively. The total amounts of the specific four allergens in the NRL gloves were 2.18 microg/g and 0.45 microg/g, respectively. We concluded that the main allergen of HCWs who have been sensitized occupationally by NRL gloves was Hev b 6.02.

Sensitivity and specificity of different skin prick tests with latex extracts in pediatric patients with suspected natural rubber latex allergy – A cohort study

Skin prick tests (SPT) with latex extracts are commonly used in the diagnostic approach of natural rubber latex (NRL) allergy. Non-ammoniated latex extracts are commonly utilized for this purpose. There is only one commercially available ammoniated latex extract for both diagnostic and therapeutic purposes. To our knowledge, no direct clinical comparisons have been made so far comparing sensitivity and specificity of different latex extracts in patients with clinically confirmed latex allergy. The objective of this study was to evaluate sensitivity and specificity of non-ammoniated or ammoniated SPT of latex extracts in children with a clinical history suggestive of NRL allergy. Forty-two subjects (age 4-15 yr), referred to our Allergy Clinic Center, with suspected clinical signs of NRL allergy were evaluated. Patients were selected according to the following inclusion criteria: pediatric patients of age above 4 yr with a suspected clinical history of urticaria, rhinoconjunctivitis and/or asthma due to sensitization to NRL. A definitive NRL allergy diagnosis was made on the identification of latex-specific IgE (>0.7 kU/l), positive glove use test and a highly indicative clinical history. NRL allergy was confirmed in 26 (62%) subjects. SPT for latex were performed with three different SPT solutions containing non-ammoniated NRL extracts (product A: Lofarma SpA, Milan, Italy and product B: Stallergenes, Milan, Italy) or an ammoniated extract (product C: ALK-Abellò, Madrid, Spain). A positive result was considered as the appearance of a wheal with a diameter >3 mm. In patients with confirmed NRL allergy, wheal mean (s.d.) diameters were 7.3 (2.1) with product C, and 5.7 (2.3) and 4.4 (1.8) with products B and A respectively (p = 0.004 C vs. B and A). Mean wheal diameters were significantly higher for product C in comparison with product B and A (p < 0.04). Sensitivity according to the different products tested was 65% (product A); 81% (product B) and 96% (product C) (p = 0.0084; C vs. A). No difference between the three products was observed regarding diagnostic specificity (94%, 88% and 94%, product A, B and C, respectively). Our study shows that diagnostic sensitivity of different latex extract for SPT could differ. In this particular clinical setting (i.e., children with NRL allergy) ammoniated latex extract shows a higher sensitivity in comparison with non-ammoniated products. This aspect should be considered in the diagnostic approach in subjects with suspected NRL allergy. In children with clinical confirmed latex allergy, sensitivity and specificity of different commercially available skin prick test could vary. Ammoniated latex extract has shown a higher sensibility in comparison with non-ammoniated products.

Natural rubber latex and chestnut allergy: cross-reactivity or co-sensitization?

Chestnut and natural rubber latex (NRL) allergy are often associated in the latex-fruit syndrome. To establish whether the concurrent NRL and chestnut IgE antibody reactivity are the results of co-sensitization or cross-reactivity. Sera from 19 patients with chestnut- and NRL-specific IgE were selected and tested for reactivity with recombinant (r) latex allergens. Cross-reactivity was explored by IgE-inhibition experiments using chestnut or NRL allergens as solid phase on ImmunoCAP. IgE-antibodies were detected to rHev b 6.01 (prohevein) in 58% of the sera, to rHev b 5 in 32%, to rHev b 12 in four of 13 sera, to rHev b 7.02 and rHev b 11 in four, and to rHev b 1 in two of 19 sera. rHev b 8-IgE antibodies were found in nine sera (47%), whereas six displayed mono-sensitization to rHev b 8 with regard to our test panel. Three of 16 sera showed IgE to cross-reactive carbohydrate determinants. In most sera recognizing rHev b 5 and/or rHev b 6.01 as major allergens the IgE-reactivity to NRL remained unaffected by chestnut extract and chestnut-IgE remained unaffected by NRL extract. Conversely, in sera with rHev b 8 as dominant allergen IgE-binding to NRL was nearly completely inhibited by chestnut and vice versa. IgE-binding to rHev b 8 was abolished by chestnut extract. Although patients have concomitant IgE antibody reactivity to chestnut and NRL, cross-reactivity could be demonstrated mainly in those patients with IgE to Hev b 8 (profilin) from NRL.

Latex Allergy within a Cohort of Not-at-Risk Subjects with Respiratory Symptoms: Prevalence of Latex Sensitization and Assessment of Diagnostic Tools

Background: Immunoglobluin E (IgE)-mediated hypersensitivity to natural rubber latex (NRL) is a major problem in allergy practice. Currently, the use of skin prick tests (SPTs) with latex extracts and specific IgE detection for the diagnosis of NRL allergy in suspected patients is directed to identification of risk factors. Many cases of NRL allergy remain undiagnosed due to misreporting of symptoms by the patients or lack of proper questions asked by the physician. Materials and Methods: A total of 6,126 subjects referred for respiratory symptoms underwent SPTs with NRL. Positive subjects were resurveyed for exposure to NRL, and specific IgE for NRL extracts and recombinant molecules was determined. Immunoblots of NRL extracts were performed to identify IgE patterns. Results: Forty-six of 3,930 sensitized subjects had a positive SPT with NRL, displaying a prevalence of NRL sensitization of 0.75% for the general and 1.2% for the sensitized population. Eleven out of 46 (23.9%) subjects could be defined as NRL asymptomatic, whereas 35 (76.1%) developed symptoms upon exposure to NRL. Specific IgE to NRL was detected for 22 (75.86%) of 29 tested sera. Seventeen out of 22 (77%) sera displayed specific IgE to recombinant allergens with most reactions to Hev b 5, Hev b 6.01 and Hev b 6.02. Immunoblots of NRL extract fractions with patients’ sera showed heterogeneous patterns. Conclusions: SPTs with NRL extract should be routinely performed in patients with respiratory symptoms. Hev b 5, Hev b 6.01 and Hev b 6.02 are the most important allergens, but further characterization of NRL extracts is needed to identify novel allergens and to clarify the role of crossreactive carbohydrate determinants.

Natural rubber latex and hymenoptera venoms share ImmunoglobinE‐epitopes accounting for cross‐reactive carbohydrate determinants

Epidemiological data on the prevalence and risk factors of latex sensitization have suggested a significant association between latex sensitization and the presence of one or more positive skin prick test responses to aeroallergens, food allergens and to one or more insect venoms. Xylose and core 3-fucose are typical complex glycans in plants and are foreign to mammals. Plant N-glycans and insect N-glycans may cross-react in humans. The aim of our study was to investigate whether there are cross-reactive IgE-binding structures in natural rubber latex (NRL) and hymenoptera venoms and to examine their nature. Hundred and twenty-five consecutive patients with insect venom allergy were screened for coincidental latex-specific IgE. IgE-binding components in the venoms from Apis mellifera and/or vespula species and in NRL extracts were characterized by IgE-immunoblotting to the natural allergen sources and determination of specific IgE to recombinant allergens. Cross-reactive components were investigated by inhibition experiments. The involvement of carbohydrates in the constitution of cross-reactive IgE-epitopes was further examined by specific IgE-binding to cross-reactive carbohydrate determinants (CCD) in bromelain and horseradish peroxidase as well as by periodate treatment. NRL glove extracts inhibited patients' serum IgE-binding to venom allergens. Vice versa, the IgE-binding to latex glove extracts could be inhibited by pre-incubation with the insect venoms. Specific IgE-binding to recombinant latex allergens was absent, whereas the cross-reactive IgE-epitopes were sensitive to periodate treatment and specific IgE to CCD (MMXF and MUXF type) could be detected. Insect venoms and NRL share IgE-binding CCD that may be responsible for positive serological test results to NRL in patients with insect venom allergy. This copositivity occurs frequently (13.6%) among venom-allergic individuals and did not elicit clinical symptoms upon contact to latex in the patients examined. In contrast, true cosensitization to insect venoms and NRL allergens can occur and may not be missed.

Sublingual immunotherapy with a latex extract in paediatric patients: a double-blind, placebo-controlled study

ABSTRACTBackground: Natural rubber latex (NRL) allergy remains an important allergic disease triggering urticaria, asthma, angioedema and anaphylaxis. Specific immunotherapy can help to solve problems related to NRL allergy. So far, no controlled clinical trials have been performed inchildren suffering from NRL allergy.Objectives: To evaluate the safety and efficacy of sublingual immunotherapy (SLIT) with a commercial NRL extract in children with NRL allergy.Research design: Randomized, double-blind, placebo-controlled, 12‐month trial.Patients and methods: Twenty-six children (aged 4–15 years) with NRL allergy, who had cutaneous and/or respiratory symptoms, including oral allergy syndrome to fruits containing cross-reactive allergens, were recruited. Twelve children were randomized to SLIT with a commercial NRL extract and eight to placebo (3:2). An additional six children with NRL allergy served as untreated controls.Main outcomes measures: A glove use test was utilized to monitor skin and systemic symptoms triggered by NRL exposure at baseline and 3, 6, 9 and 12 months later. Oral allergy symptoms were also monitored.Results: No side effects related to treatments were observed in any patient. A significant improvement of symptom score in treated patients in comparison with baseline values was observed at 3 months ( p = 0.01) and consolidated after 1 year of treatment ( p = 0.0005). In comparison with placebo, significant improvements were observed starting at 9 months from study start ( p = 0.015) and at 12 months ( p = 0.005). The number of foods triggering oral allergy symptoms increased in placebo and control subjects, but not in active treated patients ( p = 0.05).Conclusion: Latex SLIT was safe and efficacious in paediatric patients with NRL allergy.

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

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. 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. 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. 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. 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.

Immunotherapy: an option in the management of occupational asthma?

To review clinical data on immunotherapy applied to occupational asthma. There are very few studies on immunotherapy in occupational asthma. The best documented use of immunotherapy in this disorder corresponds to latex allergy among healthcare workers. There are anecdotic reports of non-well controlled studies using immunotherapy with wheat flour, African maple wood, sea squirt and rat epithelium extracts. Subcutaneous immunotherapy with natural rubber latex extract, at adequate doses, seems to be a useful treatment in reducing cutaneous and respiratory symptoms, but it should be considered as a high-risk treatment due to the appearance of systemic reactions. At present, subcutaneous immunotherapy with latex extract can only be considered experimental and must be administered by experienced allergists in a hospital setting, similarly to venom immunotherapy. Nevertheless, systemic reactions responded well to treatment. Further clinical trials on efficacy, safety and long-term effectiveness in immunoglobulin E-mediated occupational rhinitis and asthma are clearly needed. Since allergen avoidance is not always possible, no other etiologic treatment but immunotherapy can be offered to patients with occupational rhinitis/asthma.

Basophil Activation Test and specific IgE measurements using a panel of recombinant natural rubber latex allergens to determine the latex allergen sensitization profile in children

There are no documented studies that describe natural rubber latex (NRL) sensitization in children with a history of surgical intervention but without any congenital malformation (urogenital anomalies, spina bifida, etc.), although some authors have studied NRL allergy in children without a history of surgical intervention. The aim of this work was to evaluate the sensitization profile to single NRL allergens in children without spina bifida and without repeated surgical interventions, by using different recombinant and natural latex allergens in two analytical techniques: specific serum immunoglobulin E (IgE) quantification and flow cytometry determination of activated basophils expressing CD63, after stimulating cells from patients with NRL allergens. A total of 23 patients and 10 healthy children were selected. Conjunctival and in-use NRL provocation tests were carried out, as well as specific IgE determination in all patients' and controls' sera with the recombinant NRL allergens: rHev b 1, rHev b 2, rHev b 3, rHev b 5, rHev b 6.01, rHev b 6.02, rHev b 8, rHev b 9 and rHev b 11 and with NRL (k82) using appropriate ImmunoCAPs. The Basophil Activation Test (BAT) was performed with whole latex extract and with the recombinant allergens rHev b 5 and rHev b 6.01, as well as with the natural allergen Hev b 6.02. The sensitivity and the specificity of NRL-specific IgE (k82) were 100%. Positive IgE responses to rHev b 5 were found in sera of 10 children, to rHev b 6.01 in 16 and for rHev b 6.02 in 15 children's sera. Specific IgE to rHev b 8 was found in four sera of the children. We only found significant differences in sensitization to rHev b 5 in children with two or more surgical interventions compared with the non-intervened group or those with only one intervention. Specific IgE in sera of children with latex-fruit syndrome recognized rHev b 6.02, but not to rHev b 11. The patients sensitized to Hev b 8, Hev b 9 and/or Hev b 11 were atopic. The four patients presenting a positive response to the NRL profilin Hev b 8 were allergic to pollen. The BAT against whole NRL extract was positive in 22 of 23 children; against rHev b 5 in 14 of the patients studied; against rHev b 6.01 in seven cases and against nHev b 6.02 in 19 children. In all the control subjects, the results using this technique were negative. If combined rHev b 5, rHev b 6.01 and nHev b 6.02 together, BAT could detect 20 of the 23 children with latex allergy. The combined use of ImmunoCAP with all the recombinant NRL allergens and BAT with rHev b 5, rHev b 6.01 and nHev b 6.02, enabled the identification of NRL allergy in 22 of 23 patients. There is a positive and significant correlation between sensitization to Hev b 5 and the number of interventions. BAT and allergen-specific IgE determination could be used as first-line in vitro diagnostic tests in patients with NRL allergy.

Prevalencia de sensibilización a látex en personal de pabellones quirúrgicos del Hospital Clínico de la Universidad de Chile

Health care workers (HCW) are a high risk group for developing natural rubber latex (NRL) hypersensitivity and allergy. Some studies showed a correlation between time and frequency of exposure to NRL gloves and hypersensitivity, but a recent meta-analysis showed no clear evidences for such assumption. To determine the prevalence of NRL hypersensitivity and allergy in a group of HCW at the University of Chile Clinical Hospital. Ninety five HCW (aged 37+/-10 years, 59 females) were interviewed about time of exposure, atopic diseases and latex-related allergy symptoms. Different NRL extracts and seven NRL gloves brands were tested by the prick test method. Twenty four workers (25%, 95% CI = 16.9%-35.2%) were sensitized. No gender differences were found. No symptomatic cases were found in the sensitized group. In the workplace, six and two non sensitized subjects had respiratory symptoms or contact urticaria, respectively. Sensitivity to bananas, avocadoes, kiwi and chestnut was not significantly more common among latex sensitive individuals. No differences between sensitized and non sensitized subjects were observed for the presence of atopic diseases or the mean number of years at the workplace. The sensitization rate to NRL increased along with years of work, from 18.6% in patients working less than 10 years, to 28.1% in the group between 10 and 20 years and to 35% in those working more than 21 years (p=0.693). Sensitization was also related to the weekly hours of exposure: 1-10 hours, 17%; 11-20 hours, 23.5%; 21-30 hours, 50% and 31-40 hours, 28.5% (p=0.036). Sensitization increased proportionally to the years and weekly hours wearing NLR gloves. We did not find symptomatic patients in the sensitized group.

Latex allergy and skin

In this review we address the prevalence and outcome of latex allergy in health care workers (HCWs). Recent findings in natural rubber latex (NRL) allergens and trials of specific immunotherapy (SIT) are also of interest. A study involving skin prick test (SPT) screening in HCWs in Russia and adjacent countries found a prevalence of latex allergy of 1.9%. Questionnaire studies performed in Wales and in the USA identified prevalence rates of about 0.6%. An intervention undertaken at the Mayo Clinic, in which only gloves with low or undetectable allergen levels were allowed, reduced markedly the incidence of NRL allergy. Two studies, one from Finland and another from Ohio, showed that outcomes in latex-allergic HCWs are generally good. A study involving SPT screening showed that 6% of construction workers had latex allergy. A questionnaire study among allergists practicing in the USA showed that 62% performed latex SPT and 6% reported anaphylaxis, which mostly occurred while using a homemade SPT solution. Hev b 2, Hev b 5, Hev b 6.01 and Hev b 13 produced positive SPT reactions in over 60% of latex-allergic individuals. Topical application of NRL in a murine model of protein contact dermatitis caused a striking increase in prohevein-specific (Hev b 6.01) immunoglobulin E levels, together with a T-helper-2 type dermatitis. A placebo-controlled SIT trial with NRL extract alleviated cutaneous symptoms but caused some systemic reactions in latex-allergic patients. Low prevalence rates suggest that the peak of the latex allergy epidemic has already passed in HCWs. Hospital-wide interventions requiring use of low-allergen gloves reduce sensitization and changing gloves to nonlatex ones, or even using low-allergen latex gloves, in the affected individuals appears to confer adequate secondary prevention. In the USA there is an urgent need for standardized latex SPT reagent. Hev b 5 and Hev b 6.01 are major in vivo NRL allergens. Findings in mice suggest that NRL proteins eluting from latex gloves may also cause hand eczema in humans. SIT with NRL extract must still be considered an experimental treatment.

Characterization of B- and T-cell responses and HLA-DR4 binding motifs of the latex allergen Hev b 6.01 (prohevein) and its post-transcriptionally formed proteins Hev b 6.02 and Hev b 6.03.

Multiple immunoglobulin E (IgE)-binding proteins in natural rubber latex extracts have been identified. In the case of Hev b 6 a differentiation was made between the precursor protein prohevein (Hev b 6.01) and its two post-transcriptionally formed proteins, the N-terminal hevein (Hev b 6.02) and the C-terminal domain (Hev b 6.03). All three components act as independent allergens. The aim of this study was a detailed analysis of the T-cell responses and the IgE-binding capacity of Hev b 6.01, Hev b 6.02 and Hev b 6.03 by using these allergens as recombinant maltose-binding fusion (MBP) proteins and the usage of synthetic modified hevein peptides. Latex-allergic health care workers (HCWs) suffering from rhinitis, conjunctivitis, contact urticaria and/or asthma with increased specific IgE-antibodies to latex were tested for their IgE-binding capacity and T-cell reactivity (by proliferation response) to the recombinant MBP-rHev b 6.01, MBP-rHev b 6.02, MBP-rHev b 6.03, to native Hev b 6.02, to modified hevein peptides and wheat germ agglutinin (WGA). For testing of the human leucocyte antigen (HLA) class II restriction of MBP-rHev b 6.01 induced peripheral blood mononuclear cell (PBMC) responses, monoclonal antibodies against HLA-DR, HLA-DP or HLA-DQ were added. Seventeen of 18 (94%) serum samples from latex-allergic HCWs had increased levels of specific IgE to MBP-rHev b 6.01, 16 (89%) to MBP-rHev b 6.02 and 13 (72%) to MBP-rHev b 6.03. A significant difference existed between the specific IgE-values of MBP-rHev b 6.02 and MBP-rHev b 6.03 (P < 0.01). Proliferation responses of PBMC of the same 18 latex-allergic patients were positive for MBP-rHev b 6.01 and MBP-rHev b 6.03 in 83 and 67% of the tested PBMC suspension, whereas the proliferation responses induced with MBP-rHev b 6.02 or native Hev b 6.02 were very low (5.6 and 22.2%). Sera from nine additional latex-allergic patients showed specific IgE binding to the native Hev b 6.02, but none of these sera showed specific IgE binding to the modified Hev b 6.02-peptides [whereby all eight cysteine residues were substituted by serine (C --> S) or by alanine (C --> A)]. Proliferation responses induced by the modified Hev b 6.02 peptides were not significantly different from that induced by Hev b 6.02. Potential HLA-DR4Dw4(DRB1*0401)-restricted T-cell epitopes of Hev b 6.01 predicted by two computer algorithms were only found in the Hev b 6.03-part of Hev b 6.01. In the Hev b 6.01 precursor the regions responsible for IgE binding and those for inducing the T-cell proliferation responses are settled in different parts of the protein. The Hev b 6.02 domain is responsible for IgE binding and carries discontinuous B-cell epitopes whereas Hev b 6.03 is a better inducer of a proliferation response and contains HLA-DR4-binding motifs.

Profile of sensitization to individual latex allergens among health care workers allergic to natural rubber latex

Rationale We evaluated the profile of sensitization to different natural and recombinant natural rubber latex (NRL) allergens among health care workers (HCWs). Methods Thirty-nine HCWs allergic to NRL with respiratory and/or cutaneous symptoms as demonstrated by positive skin tests (ALK-Abelló) and challenges tests were studied. Specific IgE to whole NRL extract (CAPk82) and different latex allergens was measured using CAP-FEIA (Pharmacia). Results Ten percent of the sera were negative to all determinations. The percentage of positive results was as follows: k82 (82%); mix rHev b1,5,6,8 (79%); in 30 sera both measurements were positive and in 6 both were negative, in 2 cases k82 was positive and mix negative, and in 4 cases k82 negative and mix positive. rHev b1 was positive 1/32 (3%), and 6/6 to nHev b2 (100%), 5 of these sera were negative to the recombinant mix, rHev b5 and rHev b6.01, but all them were positive to k82; 11/33 rHev b5 (33%); 23/33 rHev b6.01 (70%); 7 sera were positive to rHev b5 and rHev b6.01 and 6 were negative to both; 4/29 rHev b8 (14%); 0/9 rHev b9, 0/11 rHev b10, 1/10 rHev b11 (10%) and 1/6 rHev b13 (17%). Five sera were k82(-) and some recombinants(+). Conclusions Hev b6.01 and Hev b5 are major allergens recognized by our population of HCWs. Hev b2 also seems an important allergen in some patients. CAPk82 shows a good diagnostic sensitivity similar to the recombinant mix, but the use of a panel of allergens is necessary for in vitro diagnosis in some HCWs allergic to NRL.

Quantified environmental challenge with absorbable dusting powder aerosol from natural rubber latex gloves

Background: There are few data that link quantified natural rubber latex (NRL) absorbable dusting powder aerosol to biologic responses in NRL-sensitized subjects. Methods: We conducted a study on 30 health care workers with possible occupational asthma. All the subjects but 2 had a positive skin prick test result with NRL extract. Quantified environmental challenge (QEC) with powdered NRL gloves was performed in a 7-m 3 chamber. The patients would don and discard a pair of gloves every 3 minutes up to a maximum of 60 minutes. The concentrations of NRL aeroallergen were measured by a competitive IgE immunoassay. Ocular and respiratory symptoms and pulmonary function were monitored. Results: Twenty-six patients (87%) had rhinoconjunctivitis, 19 (63%) had an asthmatic response (responders), and 1 patient developed eosinophilic bronchitis on QEC. The asthmatic responses were of the early type in 15 patients, dual in 3, and isolated late in 1 patient. The duration of exposures sufficient to elicit asthmatic responses varied from 3 to 114 cumulative minutes. Time-weighted average NRL aeroallergen concentrations during QEC with responders ranged between 199 and 1107 ng/m 3. NRL concentrations measured at various time points during exposure were reproducible. Measured concentrations of NRL aeroallergen between responders (677 ± 281 ng/m 3) and nonresponders (611 ± 351 ng/m 3) were not statistically different. The cumulative inhaled NRL aeroallergen dose required for an asthmatic response ranged between 25 to 515 ng. Conclusion: The total dose of latex aeroallergen eliciting an asthmatic response during QEC was mostly affected by the duration of exposure and varied widely from person to person. (J Allergy Clin Immunol 2003;111:788-94

Epicutaneous natural rubber latex sensitization induces localized Th2-dominate dermatitis and strong IgE response

1081 Epicutaneous Natural Rubber Latex Sensitization Induces Localized Th2-Dominated Dermatitis and Strong IgE Response Harri Tapio Alenius*, Maili Lehto*, /man Amghaiab*, Marja-Leena Majuri*, Guoying Wang*, Henrik Wolff*, Kristiina Turjanmaa§, Antti Lauerma¥ Timo Reunala§, Timo Palosuo~ *Finnish Institute of Occupational Health, Helsinki, Finland §Tampere University Hospital, Tampere, Finland ¥Helsinki University Hospital for Skin and Allergic Diseases, Helsinki ~National Public Health Institute, Helsinki, Finland In addition to immediate type I allergy symptoms, natural rubber latex (NRL) allergy may manifest as protein contact dermatitis on the hands of health-care workers and other NRL glove users. We examined the role of repeated epicutaneous (EC) sensitization with NRL proteins in the development of dermatitis and antibody response in a murine model. EC application with NRL or glove extract (GE) to the shaved and tape-stripped mouse skin, but not with phosphate buffered saline (PBS) control, produced significant influx of mononuclear cells, T cells and eosinophils to the sensitized skin sites (P<0.001). The number of degranulated mast cells in NRLor GE-sensitized skin sites was significantly higher compared to PBS-treated sites (p<0.0l). IL-4 mRNA expression was markedly increased in NRLand GE-sensitized skin sites compared to PBS-treated sites (p<0.001). Moreover, significant increase in MIPl-alpha and M1PI-beta mRNA was found in NRLor GE-sensitized skin sites (p<0.0 I). EC application with NRL induced a striking increase in total and specific IgE levels but not in IgG2a levels. In contrast, intraperitoneal (IP) immunization with NRL combined with aluminum hydroxide induced a strong IgG2a response. Interestingly, EC-application with NRL elicited strong IgE response against Hey b 6.01 but not against Hev bl. In contrast, IP immunization with NRL elicited strong IgG2a production to Hev bl but not to Hev b 6.01. These results demonstrate that EC-sensitization with NRL proteins induces Th2-dominated dermal inflammation and strong IgE response in a murine model. EC-sensitization to NRL proteins eluting from the gloves may therefore play also in man an important role in the development of hand dermatitis and NRL-specific IgE antibodies.

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Changes in rates of natural rubber latex sensitivity among dental school students and staff members after changes in latex gloves

Background: A high rate of sensitization and clinical allergy to natural rubber latex (NRL) gloves has been reported in dental students and staff members. Objective: The purpose of this study was to determine whether a change in glove use from high-protein/powdered to low-protein/powder-free latex gloves at a previously surveyed dental school reduced the prevalence of NRL sensitivity among students and staff members. Methods: A cross-sectional study was performed through use of a questionnaire and skin prick testing to low ammoniated NRL extract; the method was similar to that used in a study conducted in 1995. Analyses were performed on the entire groups as well as on a subset of senior students. Results: A total of 97 subjects (61 students and 36 staff members) completed the questionnaire and underwent skin prick testing; this compared with 131 subjects in 1995. Percentages of subjects reporting asthma symptoms, rhinitis or conjunctivitis, urticaria, or pruritis within minutes of NRL exposure were 4%, 7%, 6%, and 8%, respectively; the corresponding percentages in the 1995 survey were 7% (P = not significant), 13% (P = not significant), 20% (P = .004), and 22% (P = .005). Results were similar for the subset of senior students, but in addition there were also significantly fewer complaints of rhinoconjunctivitis in 2000 than in 1995 (0% and 12%, respectively; P = .007). Of 97 subjects who underwent skin prick testing, 3 (3%) had positive skin prick test responses of 2+ or greater to NRL; this compared with 13 (10%) of 131 subjects in 1995 (P = .03). There were 3 positive skin test responses among staff members in 2000; there were none among students. Conclusions: Our results suggest a preventive effect on NRL allergy in dental students from the change to low-protein/powder-free NRL gloves in the dental school. (J Allergy Clin Immunol 2002;109:131-5.)