Occupational and food allergy: focus on allergen extracts

The aim of this thesis is, first, the diagnostic work-up of occupational and food allergies in the absence of well-validated commercially available standardised extracts for Skin Prick Test. Second, to investigate cross-reactivity in occupational and food allergic patients. Third, the treatment of, employees with an occupational allergy in order to enable the continuation of work. The number of work-related symptoms among greenhouse workers is increasing and the prevalence of food allergies is rising. The sequence of diagnostic procedures is the history first, followed by skin tests and RAST tests, and challenge tests as final instruments. Unfortunately, commercial standardised extracts to diagnose the more uncommon allergies caused by relatively unknown allergens are generally not available. Therefore, we made new in house manufactured extracts, for the diagnosis of occupational and food allergies e.g. several flower pollen, A. cucumeris, latex, fruits (peach, kiwi, banana, avocado), and hazelnut

Mono-sensitisation to peanut component Ara h 6: a case series of five children and literature review

Here, we summarise the current clinical knowledge on Ara h 6 sensitisation and clinical relevance of this sensitisation pattern using five illustrative clinical cases. The literature search yielded a total of 166 papers, and an additional relevant article was found by ‘snowballing’. A total of ten articles were considered relevant for this review. Most studies included patients with a sensitisation to Ara h 6 and cosensitisation to Ara h 2. Only three studies showed patients with a mono-sensitisation to Ara h 6. This illustrates that Ara h 6 mono-sensitisation has been neglected in literature. We present a case series of five children with sensitisation to peanut component Ara h 6. Only one of these five patients showed Ara h 8 cosensitivity. Three out of the five children had a positive double-blind placebo-controlled food challenge (DBPCFC), with moderate to strong reactions. Conclusion: A mono-sensitisation to peanut component Ara h 6 is uncommon but can cause severe allergic reactions. Therefore, the determination of sIgE to Ara h 6 is warranted in patients with a suspected peanut allergy, especially in the absence of sensitisation to Ara h 1, 2, 3 and 9.(Table presented.

Occupational allergy in Strawberry Greenhouse workers

Background: Employees in strawberry greenhouses are highly exposed to several (potential) allergenic agents. However, no occupational allergy in this branch has been described before. First, the presence of work-related allergic symptoms in strawberry workers was explored. Second, we aimed to prove the concept that an IgE-mediated allergy could be responsible for work-related symptoms. To test the possibility of an IgE response secondary to cross-reactivity to birch or grass pollen, inhibition experiments were performed. Methods: First, a questionnaire survey concerning work-related allergic symptoms among strawberry workers in the Netherlands was carried out. Second, 3 workers with work-related symptoms were investigated in detail. Skin tests, serum-specific IgE tests with home-made extracts of strawberry pollen and other possible allergenic agents of the strawberry greenhouse environment were executed. Furthermore, immunoblots and nasal provocations with strawberry pollen extract were performed. In addition, inhibition experiments were performed. Results: 29 of 75 questionnaire respondents (38.7%) reported work-related symptoms. Sensitization to strawberry pollen was found in skin tests in all 3 employees with work-related symptoms. ELISA and immunoblotting with strawberry pollen showed positive results in 2 employees. Birch and grass pollen failed to inhibit IgE binding to strawberry pollen in 1 of 2 employees. Partial inhibition was seen in the second employee. Nasal provocation validated clinically relevant allergy to these pollens in 2 of 3 subjects. Conclusions: Allergic symptoms attributable to the workplace are present among a proportion of strawberry greenhouse employees. An IgE-mediated occupational allergy to strawberry pollen may contribute to these symptoms

Honeybees as an aid in improving labour conditions in sweet bell pepper greenhouses: reduction of pollen allergy

Sweet bell pepper is the most important greenhouse vegetable crop in the Netherlands. It is grown on an area of 10,000 hectares, and about 8000 people are working in these greenhouses. One third of these workers sooner or later develop an occupational allergy to the sweet bell pepper pollen. The symptoms range from itching, blocking of the nose as well as a sniffling nose, to asthma. The pollen falls down from the flowers when the plants are shaken, which occurs when people are cutting fruits or when they prune or twine the plants. In a pilot study, a number of greenhouses in which honey-bee colonies were introduced were compared with greenhouses without honey-bees. In the greenhouses with honey-bees, hardly any pollen was present on the anthers of the flowers, since it was collected by the honey-bees as a food for their larvae. In flowers of plants in greenhouses without honey-bees, pollen was present most of the time. The symptoms of allergic workers in the greenhouses were significantly reduced by the presence of honey-bees, as was deduced from questionnaires in which the workers were asked to mark the intensity of the symptoms during the past two weeks on a Visual Analogue Scale. The possible beneficial impact of the application of honey-bees on a larger scale needs further research, as well as answering the question of a possible prevention of this occupational allergy in sweet bell pepper horticulturists by honey-bees. The required or optimal number of bee colonies per area greenhouse needs also to be studie

The effect of birch pollen immunotherapy on apple and rmal d 1 challenges in adults with apple allergy

Background: A proportion of patients allergic to birch pollen are also allergic to pit fruit. The objective of this study was to investigate the effect of immunotherapy with birch pollen on birch-pollen-related apple allergy. Method: Patients with birch pollen immunotherapy underwent a skin-prick test with birch pollen, apple and rMal d 1, global assessments and nasal challenges with birch pollen, open food challenge with apple and a double-blind, placebo-controlled test with rMal d 1 at the start of and during the immunotherapy. Measurements of specific IgE in response to Bet v 1 and rMal d 1 and IgG4 in response to Bet v 1 and rMal d 1 took place. Results: Six of eight patients demonstrated an improvement of nasal challenge test results and all patients improved on global assessment during the immunotherapy. The median oral dose of apple required to elicit a reaction increased but was not statistically significant. The patients showed a decrease in skin-prick test values in response to birch pollen (1.05 to 0.36), apple (0.78 to 0.25) and rMal d 1 (0.51 to 0.10) with p-values of 0.04, 0.03 and 0.06, respectively and a decrease of specific IgE in response to Bet v 1 (10.66 kU/L to 5.19 kU/L) and rMal d 1 (0.99 to 0.61 kU/L) with p-values of 0.01 and 0.05, respectively. Only the median specific IgG4 value to Bet v 1 increased from 0.05 to 1.85 mg/L (p-value of 0.02) and not to IgG4 rMal d 1 (0.07 to 0.08 kU/L). Conclusion: The beneficial effects of immunotherapy for birch pollen were accompanied by a limited effect on apple allergy

A meta-analysis of baseline characteristics in trials on mite allergen avoidance in asthmatics: Room for improvement

Background: Evidence regarding the clinical effectiveness of mite allergen avoidance for the treatment of asthma is lacking. In previous meta-analyses on mite allergen control, the baseline data were not discussed in detail. This study updates and extends the existing Cochrane review by Gøtzsche and Johansen (Cochrane Database of Systematic Reviews, 2008, Art. No: CD001187), with a focus on baseline asthma outcomes and allergen exposures. Methods: We used the existing trials in the original Cochrane review and included newly published studies. The baseline data for the mite allergen load from the mattress, the standardized asthma symptom score (ASS), the forced expiratory volume in 1 s percentage of predicted (FEV1 %pred.), and the histamine provocative concentration causing a 20% drop in FEV1 (PC20) were extracted. First, the mean values of the outcomes were calculated. The influence of the mite allergen load was examined with a random-effect meta-regression using the Metafor package in R. Results: Forty-five trials were included; 39 trials reported strategies for concurrent bedroom interventions, and 6 trails reported strategies for air purification. The mite allergen load ranged from 0.44 to 24.83 μg/g dust, with a mean of 9.86 μg/g dust (95% CI 5.66 to 14.05 μg/g dust, I2 = 99.8%). All health outcomes showed considerable heterogeneity (standardized ASS mean: 0.13, 95% CI 0.08 to 0.18, I2 = 99.9%; FEV1 %pred. mean: 85.3%, 95% CI 80.5 to 90.1%, I2 = 95.8%; PC20 mean: 1.69 mg/mL, 95% CI 0.86 to 2.52 mg/mL, I2 = 95.6%). The covariate mite allergen load did not significantly influence health outcomes. Discussion: This meta-analysis shows that mite avoidance studies are characterized by the inclusion of patients with rather mild to moderate asthma and with varying and sometimes negligible levels of allergen exposure. Future studies should focus on patients with severe asthma and increased levels of allergen exposure

Effectiveness of the Air Purification Strategies for the Treatment of Allergic Asthma: A Meta-Analysis

We updated the meta-analysis published by McDonald et al. [Chest 2002;122;1535-1542] by reviewing the effectiveness of air purification for the treatment of home-related allergic asthma (dust mite, dog, cat, and cockroach). We analysed the trials included by McDonald et al. as well as studies published since 2000. Data on asthma symptoms scores (ASS), medication use, forced expiratory volume in 1 s as a percentage of the predicted value (FEV1 %pred), histamine provocative concentration causing a 20% reduction in FEV1 (PC20), Asthma Quality of Life Questionnaire (AQLQ) scores, and fractional exhaled nitric oxide (FeNO) levels were extracted. The effectiveness was examined using metafor (registered in Prospero CRD42019127227). Ten trials including a total of 482 patients (baseline characteristics: mean FEV1 %pred 83.2%, I2 = 96.7%; mean PC20 4.93 mg/mL, I2 = 44.0%; mean AQLQ 4.67 [max. 7], I2 = 93.7%; mean FeNO 36.5 ppb, I2 = 0%) were included. We assessed the mean differences in the AQLQ scores as +0.36 (95% CI 0.10 to 0.62, p = 0.01, n = 302, I2 = 0%) and the FeNO levels as -6.67 ppb (95% CI -10.56 to -2.77, p = 0.0008, n = 304, I2 = 0%). The standardised mean differences in all other health outcomes were not significant (ASS -0.68, p = 0.20; medication use: -0.01, p = 0.94; FEV1 %pred -0.11, p = 0.34; PC20 +0.24, p = 0.53). We found statistically significant mean differences in the AQLQ scores and FeNO levels in patients with predominantly mild to moderate asthma at baseline. A large trial reported great improvement in the subgroup of patients receiving Global Initiative for Asthma step 4 therapy. We recommend that future studies on air purification focus on patients with severe and poorly controlled allergic asthma