Occupational allergy due to spider mites: Tetranychus urticae (Koch) and Panonychus citri (Koch)

Background Allergy to both house dust and storage mites is well established, but information about other species of mites is seant. Objective One hundred and fifty patients directly exposed to an occupational environment were studied to assess whether spider mites (Tetranychidue) caused their allergic symptoms. We also studied a group of 50 patients from an urban environment, who were not occupationally exposed to spider mites, with a strong sensitization to Dermatophagoides pteronyssinus (RAST class 4). Methods Case history (including questions about work-related symptoms), skin tests, RAST and conjunctival provocation tests were performed in both groups using Tetranychus urticae and Panonychus citri extracts as allergens. Cross-reactivity between spider mites and D. Pteronyssinus was determined by RAST inhibition. Results Fifty-four of 150 rural workers were positive to Tetranychidae and in all cases there was an associated sensitization to D. pteronyssinus. All individuals belonging to the urban group were positive to spider mites. RAST inhibition demonstrated a significant cross-reactivity between Tetranychidae and D. pteronyssinus. Five of fifty-four rural workers sensitized to spider mites developed symptoms only when they handled plants or fruits infested with spider mites and they became asymptomatic when exposure ceased. Conclusion In the rural population studied. 36% of workers were found to be sensitized to spider mites and 10% had symptoms associated with occupational exposure. Since specific IgE antibodies to spider mites could not be detected in the absence of the specific IgE antibodies to D. pteronyssinus, and as all the affected workers were RAST positive to D. pteronyssinus, prior sensitization to house dust mites may be a risk factor for occupational allergy to spider miles.     

Lupin allergy in peanut-allergic children and teenagers

Background:  Lupin has now been introduced into food production in the UK. There is a concern that, on account of cross-reactivity, peanut-allergic children are at high risk for lupin allergy.
Aims:  To investigate the prevalence of lupin sensitization and allergy in children with peanut allergy compared with atopic controls.
Methods:  Children (<18 years) were recruited. Peanut-allergic subjects either had a convincing history of peanut allergy with diagnostic peanut skin prick test (SPT) or specific-immunoglobulin E (IgE) results or a positive food challenge. Control subjects were atopic but not peanut-allergic. All subjects had SPT to peanut and lupin. Sensitized subjects were offered a randomized, double-blind, placebo-controlled lupin challenge. Lupin allergy was defined as objective immediate hypersensitivity reaction at food challenge.
Results:  Forty-seven peanut-allergic children and 46 atopic controls were recruited. Sixteen peanut-allergic children were sensitized to lupin [34%, 95% confidence interval (CI): 21–49%]. Nine were challenged to lupin. Two reacted (itchy mouth and urticaria; itchy mouth and 20% drop in peak expiratory flow rate) giving a minimum prevalence of lupin allergy in peanut-allergic children of 4.0% (95% CI: 1–15%). Atopic controls were significantly ( P  = 0.001) less likely to be sensitized to lupin (4%, 95% CI: 1–15%) and had smaller wheals and serum-specific IgE results. None of the atopic controls reacted on lupin challenge, giving a rate of allergy in the atopic controls of 0% (95% CI: 0–8%).
Conclusions:  A small but significant number of children with peanut allergy are allergic to lupin. Sensitization to lupin is much rarer in nonpeanut-allergic atopic subjects.     

Allergy to millet: another risk for atopic bird keepers

BACKGROUND: Millet has been reported to induce not very frequent but severe anaphylactic reactions following ingestion. Seven individuals who all kept cage birds experienced allergic reactions after ingestion of millet-containing food. METHODS: We investigated the immunoglobulin E (IgE)-reactivity of these individuals to millet employing immunoblotting, RAST and skin prick tests. As the sensitization possibly occurred via the inhalant route we investigated millet-specific IgE levels of 16 additional sera from bird keepers with proven atopy, in retrospect. RESULTS: All patients who had experienced reactions after ingestion of millet displayed millet-specific IgE. Sixty-three percent of the atopic bird keepers possessed millet-specific IgE. By means of immunoblotting three major allergens in millet extract were detected. CONCLUSIONS: Our results indicate that millet plays an important role as inhalant allergen for atopic bird keepers. A sensitization to millet may subsequently also elicit food allergy.     

Urticaria and rhinitis to shrubs of Ficus benjamina and breadfruit in a banana-allergic road worker: evidence for a cross-sensitization between Moracea, banana and latex.

BACKGROUND: We report the case of a road worker with a food allergy to banana, who developed urticaria and rhinitis when cutting shrubs of Ficus benjamina and breadfruit. He did not develop an allergy to latex of Hevea brasiliensis. RESULTS: Sensitization to latex of F. benjamina, H. brasiliensis, breadfruit and banana was demonstrated using skin tests and specific IgE measurements. RAST inhibitions procedures showed that specific IgE to breadfruit latex cross-reacted more strongly with latex of H. brasiliensis and banana than with latex of F. benjamina with the same extract. CONCLUSION: Given the wide distribution of Moracea trees in tropical regions, sensitization to latex of H. brasiliensis and banana could be a consequence of sensitization to Moracea members; F. benjamina does not seem to be the only Moracea responsible for cross-allergy with latex and fruit. Consequently, it seems interesting to test other members of the Moracea family in patients sensitized to latex of H. brasiliensis and banana. Sensitization to breadfruit could be a risk factor for sensitization to latex of H. brasiliensis.     

IgE to Bet v 1 and profilin: cross-reactivity patterns and clinical relevance

BACKGROUND: Individuals with pollen allergy often have IgE against plant-derived foods. This can be due to cross-reactive IgE against Bet v 1 and homologues, profilins, and/or cross-reactive carbohydrate determinants. OBJECTIVE: The aim of this study was to correlate sensitization to Bet v 1 and profilin with individual recognition patterns to plant foods and clinical relevance. METHODS: Fifty-two patients with pollen allergy and IgE against at least one plant-derived food were included in the study. Adverse reactions to plant-derived foods were documented by using standardized interviews. Skin prick tests were performed for pollen (grass, birch, and mugwort) and 14 plant-derived foods. In addition, recombinant (r) Bet v 1 and rBet v 2 (profilin) were tested intracutaneously. Specific IgE against the abovementioned allergens were determined by means of RAST. Cross-reactivity was studied by means of RAST inhibition. RESULTS: Eighty-five percent of patients were sensitized to Bet v 1, and 71% were sensitized to profilin. Profilin was associated with a higher number of positive RAST results to plant-derived foods than Bet v 1. In contrast, Bet v 1 was associated with more positive skin prick test responses and more food-related symptoms. Sensitization to Bet v 1 was associated with IgE against apple, hazelnut, and peach, whereas sensitization to profilin was associated with positive RAST results to all investigated plant-derived foods except apple, peach, and melon. CONCLUSIONS: IgE antibodies against Bet v 1 have a more limited spectrum of cross-reactivity than those against profilin, but they frequently give rise to clinically relevant cross-reactivities to food. In analogy to anticarbohydrate IgE, cross-reactive IgE against food profilins have no or very limited clinical relevance.     

Sensitization to oilseed rape is not due to cross-reactivity with grass pollen

BACKGROUND: Oilseed rape is an important crop grown in the UK which can cause specific immunological sensitization with clinical symptoms in a relatively small number of the general population. Individuals with immunoglobulin (Ig) E-mediated allergy to oilseed rape have also been found to be sensitized to other pollen allergens, most frequently being grass pollen. Cross-reactivity between common grass and oilseed rape would have important implications, especially as their flowering period coincides. OBJECTIVE: We have investigated whether the cosensitization found in individuals sensitized to both oilseed rape and grass pollen is due to cross-reactivity. METHODS: Cross-reactivity between oilseed rape and grass pollen was determined using RAST, RAST inhibition, Western blotting and inhibition studies with Western blotting. RESULTS: Competitive RAST inhibition studies between pollen of oilseed rape and grass failed to show any cross-reactivity between the pollen types. Self-inhibition with oilseed rape resulted in 90% inhibition, whereas there was less than 10% inhibition with grass pollen. Western blotting revealed allergens of similar molecular weight in both oilseed rape and grass pollen. Despite allergens of similar molecular weights being present in both pollen types, inhibition immunoblot studies confirmed that the allergens in the two allergens were immunologically distinct. CONCLUSION: The allergens of oilseed rape and grass pollen, although similar in molecular weights, are immunologically distinct and there is no evidence of cross-reactivity between them. Individuals allergic to grass pollen will not necessarily develop a specific nasal or airway response to inhaled oilseed rape pollens.     

Characterization of occupational sensitization by multiallergen immunoblotting in workers exposed to laboratory animals

BackgroundStudies have estimated that 10% to 23% of workers exposed to laboratory animals report symptoms of laboratory animal allergy.ObjectivesTo determine the level of occupational sensitization in workers exposed to laboratory animals and to develop a diagnosis system based on a multiallergen IgE immunoblot.MethodsA total of 75 workers exposed to laboratory animals were initially studied with skin prick tests performed with animal epithelia extracts. The workers with suspected occupational disease and positive skin prick test results were further studied with the ImmunoCAP system to determine specific IgE levels to urine and epithelia allergens and with multiallergen IgE immunoblotting to detect specific IgE levels to epithelia allergens and bovine serum albumin.ResultsTwenty of the 75 workers were studied with ImmunoCAP and multiallergen IgE immunoblotting. Nine were polysensitized and 3 were sensitized to only one animal. The results obtained by ImmunoCAP and multiallergen IgE immunoblotting were concordant except for in 3 workers, who had low or negative values of specific IgE determined by ImmunoCAP but positive allergen detections by immunoblotting. On the basis of the results of the study and the clinical symptoms related by workers, 16% were diagnosed as having occupational allergy.ConclusionsMultiallergen immunoblotting by means of a unique test offers a graphic representation of sensitization to the different animals to which workers are exposed, providing additional information on the clinical symptoms caused by the involved allergens. The results presented suggest that this system can improve the diagnosis of laboratory animal allergy by obtaining a sensitization profile for each exposed worker.     

RAST with animal dander, urine, saliva and serum

Binding of specific IgE antibodies from the sera of patients allergic to animals was investigated by direct RAST, using the animal's dander, urine, saliva or blood serum as insolubilized allergens. In allergy to rat, mouse, guinea pig, dog, cat or horse, the RAST results with the excretions of a particular animal were mutually well correlated. RAST with the animal blood serum was positive less often, and only in cases of a positive dander RAST. It is concluded that a RAST with animal dander precludes the use of other animal products.     

Working with male rodents may increase risk of allergy to laboratory animals

BACKGROUND: Our aim was to study the risk of laboratory animal allergy (LAA) among research staff working in laboratories separate from the animal confinement area. The roles of atopy and exposure intensity in LAA were studied with special regard to exposure to male rodents, who excrete higher levels of urinary allergens than female rodents. METHODS: Eighty rodent-exposed subjects gave blood samples for the analysis of total IgE, Phadiatop, and specific IgE against rat (RUA) and mouse urinary allergens (MUA), and answered questionnaires. Air samples were collected for RUA and MUA aeroallergen measurement in both laboratories and animal confinement facilities. RESULTS: Twenty percent of the subjects had IgE >0.35 kU/l to RUA and/or MUA, and 32% had experienced animal work-related symptoms, although 90% of aeroallergen samples from the research department laboratories were below the detection limit (<0.26 ng RUA per m(3) and <0.8 ng MUA per m(3)). Atopy (positive Phadiatop), total IgE >100 kU/l, other allergies (especially to other animals), or more than 4 years of exposure significantly increased laboratory animal sensitization and symptoms. Working with mainly male rodents gave odds ratios (95% CI) of 3.8 (0.97-15) for sensitization and 4.4 (1.4-14) for symptoms. Subjects with both exposure to mainly male rodents and atopy or elevated total IgE had a 10-fold higher frequency of sensitization than exposed subjects with neither risk factor. CONCLUSION: A majority of subjects with a combination of exposure to mainly male rodents and atopy or elevated total IgE developed sensitization to and symptoms from laboratory animals. Current low exposure seems to maintain the presence of specific IgE. Further measures must be undertaken to provide a safe workplace for laboratory animal workers.     

Determination of the T cell epitopes of the lipocalin allergen, Rat n 1

BACKGROUND: Laboratory animal allergy (LAA) is an important cause of occupational sensitization and asthma. Rats are a frequent cause of LAA and the major rat allergen, Rat n 1, is a member of the lipocalin protein family, which includes several other animal allergens such as the cow allergen, Bos d 2. To date, Bos d 2 is the only mammalian lipocalin allergen to have been studied in detail. OBJECTIVE: We undertook a cross-sectional study of a large population of individuals exposed to laboratory rats to determine the proliferative responses of peripheral blood mononuclear cells (PBMCs) to the major rat allergen, Rat n 1. METHODS: Eighty-three cases (defined by a positive skin prick test (SPT) > or =3 mm and/or a positive RAST > or =2% binding) and 274 referents without specific IgE to rats were tested for their proliferative responses of PBMCs to rat allergen. Cytokine release to rat urinary protein was examined in 28 sensitized and 42 non-sensitized exposed individuals. RESULTS: Proliferation to rat urinary protein was weak in all individuals. Four regions within Rat n 1 were identified as containing potential immunodominant T cell epitopes and three of these co-localized within the conserved regions of the lipocalin molecule. All four regions within Rat n 1 overlapped considerably with the characterized epitopes of the lipocalin allergen, Bos d 2. IL-5 and ratios of IL-5/IFN-gamma were significantly increased in cases. CONCLUSION: The response to Rat n 1 is remarkably similar to the cow lipocalin allergen Bos d 2. T cell epitopes within lipocalins appear to co-localize with the conserved regions of the molecule. LAA is characterized by an increased production of IL-5. Investigation of other lipocalin allergens will provide further information about the allergenicity of this group of proteins.     

Allergy to jackfruit: a novel example of Bet v 1-related food allergy

BACKGROUND: Jackfruit allergy has been reported just once. It is unknown whether this food allergy is caused by direct sensitization or cross-sensitization to pollen allergens. OBJECTIVE: Establish whether jackfruit allergy is linked to birchpollen allergy. METHODS: Two jackfruit allergic patients and five patients with birchpollen-related apple allergy were recruited. Sensitization to pollen and plant foods was assessed by skin prick test (SPT), radio-allergosorbent test (RAST) and immunoblot. RAST analysis was performed for Bet v 1 and Mal d 1. Cross-reactivity was evaluated by RAST and immunoblot-inhibition. Biological activity of immunoglobulin E (IgE) was measured by basophil histamine release. Allergy to jackfruit was evaluated by double-blind placebo-controlled food challenge (DBPCFC) or open challenge (OC). RESULTS: In both patients DBPCFC confirmed the reported jackfruit allergy. SPT was 41 and 27 mm2 and specific IgE to jackfruit was 5.9 and 0.8 IU/ml, respectively. Immunoblot analysis revealed IgE reactivity at Mr of approximately 17 kDa. The Bet v 1-related nature of this allergen in jackfruit was demonstrated by RAST and immunoblot inhibition. To assess whether jackfruit allergy might be common in patients with combined birchpollen-fruit allergy, five such patients underwent an OC with jackfruit. All five had OA-like symptoms. CONCLUSIONS: Jackfruit allergy can be added to the list of birchpollen-related food allergies. Increased consumption of this fruit will result in a rise in allergic reactions.     

Primary sensitization to sweet bell pepper pollen in greenhouse workers with occupational allergy

BACKGROUND: In a previous investigation, a high prevalence of allergy to sweet bell pepper pollen was found among exposed horticulture workers. Allergy to plant-derived food is often the consequence of primary sensitization to common pollen allergens. OBJECTIVE: We therefore investigated the cross-reactivity between sweet bell pepper pollen and pollen from grass, birch or mugwort. METHOD: We selected 10 sera from greenhouse workers who had, besides specific IgE against sweet bell pepper pollen, also IgE to grass, birch or mugwort pollen. Cross-reactivity was tested by the inhibition of IgE binding to solid-phase coupled sweet bell pepper pollen extract. The 10 sera were also analysed for IgE binding to sweet bell pepper pollen by immunoblotting. RESULTS: With these sera, no or small inhibition of IgE binding to sweet bell pepper pollen extract was observed with grass, birch and mugwort pollen. With immunoblotting, major IgE-binding structures were seen at 14, 29 and 69 kDa in sweet bell pepper pollen extract. CONCLUSION: The results of our study demonstrate that sweet bell pepper pollen contains allergens that have no or limited cross-reactivity with common pollen allergens. With sera from the 10 patients tested, sensitization to sweet bell pepper pollen was not the consequence of primary sensitization to common pollen allergens.     

Allergy to honey: relation to pollen and honey bee allergy

To identify the allergenic components of honey we studied 22 patients with a history of systemic allergic symptoms following honey ingestion. The group of honey-allergic patients was compared with three control groups: 10 subjects sensitized to artemisia, 10 with honey bee venom allergy and 10 without a history of atopy or bee sting reactions. The allergological tests included skin tests and RAST with three different kinds of Swiss honey (dandelion, forest and rape), pollen of compositae species, celery tuber, extract of bee pharyngeal glands, honey bee venom and bee whole body extract. The results show that 3/4 of honey-allergics are sensitive to dandelion honey and 13 of 22 also to compositae pollen. Nine of the honey allergic patients were sensitized to honey bee venom, 3 also to bee pharyngeal glands and to bee whole body extract. Analysis of diagnostic tests and RAST inhibition studies suggest that besides compositae pollen other allergens, most likely of bee origin are important. In honey allergics primary sensitization may be due either to the honey itself, to airborne compositae pollen or even to cross-reacting bee venom components.     

Prevalence of allergic sensitization to inhalant allergens among blood donors in Kuwait - a desert country

Kuwait is a desert country where the prevailing high temperatures, low humidity, and scant vegetation suggest a low prevalence of allergy. We evaluated the prevalence of atopic sensitization (presence of allergen-specific IgE) among young adult blood donors by screening a total of 505 subjects (male : female ratio 1.6) with mean age of 28.4 years (range 18–50 years). The Pharmacia CAP-Phadiatop® test, which detects serum IgE specific to most common airborne allergens, was used. Some of the specific sensitizing allergens were also identified by the related CAP-RAST method. Sensitization was detected in 223 of the 505 subjects (44.2%) screened. Kuwaiti nationals had a significantly higher prevalence rate (50.2%) than non-Kuwaitis (34.2%) (χ²= 8.6, P<0.003). The highest prevalence rate was found among male Kuwaitis (53.8%). The prevalence of current or previous allergic disease (subject-reported) was 20.6%. Bermuda grass, house-dust mite ( Dermatophagoides pteronyssinus ), and Chenopodium album were the most prevalent sensitizing allergens, with frequencies of 53.6%, 52.7%, and 50.9%, respectively, among the sensitized subjects (corresponding to 23.7%, 23.3%, and 22.5%, respectively) for the entire population. Sensitization increased with age, but only among the expatriates, younger Kuwaitis being as frequently sensitized as the older ones. Polysensitization was found to be common. Of the 109 CAP-RAST-positive subjects, 71 (65.1%) were sensitized to more than one allergen, and 30 of these (42.3%) were sensitized to four or more allergens. These results show that atopy is highly prevalent among young adults in Kuwait, and the higher prevalence rate among nationals than expatriates suggests the involvement of genetic or local environmental factors. The results also confirm that mite and plant pollens may be major sensitizing allergens even in a desert environment.     

Prevalence of sensitization to Tetranychus urticae in greenhouse workers

BACKGROUND: Tetranychus urticae (TU) is a macroscopic mite which infests a large number of plants of economic interest worldwide. It has recently been described as a cause of occupational allergic disease in greenhouse workers. However, there are no epidemiological data concerning the prevalence of TU allergy in an unselected exposed population. OBJECTIVE: The aims were to study the prevalence of TU sensitization among greenhouse workers and its relationship to the working environment and to personal factors. METHODS: We studied 246 consecutive greenhouse workers, recruited directly from the field. A clinical and epidemiological questionnaire, a skin-prick test (SPT) to TU and common allergens and TU-specific IgE (RAST) determinations were performed. Seventy-five healthy volunteers and 152 atopic patients were used as a control group. RESULTS: The prevalence of a positive SPT to TU was of 25%. Forty-five workers (19%) were TU-allergic, occurring more often in atopic greenhouse workers (P < 0.0001). Seven per cent showed asymptomatic sensitization. The time of exposure to TU was significantly greater in the TU-allergic patients (P < 0.05). The probability of sensitization to TU was 3.7 times greater in exposed than in non-exposed subjects (P < 0.0001). CONCLUSIONS: In this study, the prevalence of TU sensitization was 25%. There were significant associations with TU allergy and atopy and the time of exposure to TU.     

Exposure-response relationships for work-related sensitization in workers exposed to rat urinary allergens: results from a pooled study

BACKGROUND: Recent studies in a few industries have shown that the likelihood of IgE-mediated sensitization increases with increasing exposure. The shape of the exposure-response relationships and modification by age, sex, and smoking habit has hardly been studied. OBJECTIVE: The purpose of this study was to determine exposure sensitization relationships for rat sensitization and to evaluate the influence of atopy, smoking habits, and sex. METHODS: Data from 3 cross-sectional studies in The Netherlands, the United Kingdom, and Sweden were used and involved 1062 animal laboratory workers. Selection criteria were harmonized, and this resulted in a study population of 650 animal laboratory workers (60.6% female) with less than 4 years of exposure. Air allergen levels were assessed previously and converted on the basis of an interlaboratory allergen analysis comparison. Available sera were analyzed for the presence of specific antibodies against common allergens (house dust mite, cat, dog, and grass and birch pollen) and work-related allergens (rat and mouse urinary proteins). Questionnaire items on work-related respiratory symptoms, hours worked with rats per week, job performed, smoking habits, and sex were used in this analysis RESULTS: The prevalence of work-related sensitization to rat urinary allergens (IgE >0.7 KU/L) was 9.7 % (n = 63). Thirty-six of the sensitized workers had work-related symptoms (asthma or rhinitis). Two hundred forty-eight workers (38.2%) were atopic (defined as specific IgE to 1 of the common allergens). The sensitization rate increased with increasing air allergen exposure. Atopic workers exposed to low levels of allergen had a more than 3-fold increased sensitization risk compared with nonexposed atopic workers. For atopic subjects, the risk increased little with increasing exposure, whereas for nonatopic subjects, a steadily increasing risk was observed. Smoking and sex did not modify the sensitization risk. CONCLUSION: Rat urinary allergen-sensitization risk increased with increasing exposure intensity. Workers who were atopic had a clearly elevated sensitization risk at low allergen exposure levels.     

Allergenic composition of the mite Suidasia medanensis and cross-reactivity with Blomia tropicalis

BACKGROUND: Mites of the genus Suidasia are commonly found in house dust and may play an allergenic role in exposed populations. However, the allergenic potential and clinical impact of this genus has not been well established. The main objective of this project was to evaluate the allergenic role of the mite Suidasia medanensis. METHODS: An extract of S. medanensis was prepared and the allergen composition determined by immunoblot. Specific IgE antibody levels to S. medanensis and Blomia tropicalis were evaluated by radioallergosorbent (RAST) in the sera of 97 allergic asthmatic patients and 50 nonallergic subjects. Cross-reactivity between S. medanensis and the mite species B. tropicalis and Dermatophagoides farinae was investigated by RAST and immunoblot inhibitions. RESULTS: Seventy-one asthmatic patients sera (73.2%) had positive IgE reactivity to S. medanensis; 14 allergens with molecular weights ranging from 7.5 to 105 kDa were detected. The most frequently detected had molecular weights of 30-31 (54.8%), 24.5 (42%), 21 (38.7%), 47 (35%) and 58 kDa (35.5%). Blomia tropicalis extract inhibited IgE binding to nine of these identified allergens. Four B. tropicalis allergens were inhibited by S. medanensis extract. RAST inhibition results demonstrated a high degree of inhibition by B. tropicalis (87.2%) and D. farinae (90.9%) than by S. medanensis (32%). CONCLUSIONS: Sensitization to S. medanensis is common in asthmatic allergy patients in Cartagena. An important degree of cross-reactivity was established between S. medanensis and B. tropicalis, and D. farinae.     

Impact of cross‐reactive carbohydrate determinants on wood dust sensitization

Background Occupational wood dust exposure can induce allergy and may be one cause of respiratory health problems among woodworkers. Objective The objective was to determine the prevalence and quantitative level of specific immunoglobulin E (sIgE) to beech and pine wood in exposed workers. Wood sensitization was specified with regard to cross‐reactivity and was correlated to the reported symptoms. Methods Danish workers (n=701) were investigated for sIgE to beech and pine. Wood samples from workplaces were analysed and coupled to ImmunoCAPs. Workers sensitized to wood were tested for cross‐reactive carbohydrate determinants (CCDs) and environmental allergens. IgE binding was specified for glycogenic vs. proteinogenic epitopes by inhibition tests. Results The prevalence of wood sensitization among all workers was 3.7%. There was no association between sensitization prevalence or sIgE concentrations and self‐reported allergic symptoms. Beech‐ and pine‐sensitized workers showed a high prevalence of CCD sensitization (73%). However, workers with a single sensitization to wood had no sIgE to CCDs. Specifying IgE epitopes demonstrated that sera of workers reporting allergic symptoms recognized proteinogenic IgE‐epitopes on wood allergens, whereas workers without allergic symptoms had primarily sIgE‐epitopes to glycogenic structures. Although 96% of the wood‐sensitized workers were atopic, no significant correlation was found between wood sensitization and sIgE to beech and birch pollen, but an association was found between sIgE against CCDs and pine pollen. Conclusion Sensitization prevalence to beech and pine wood measured by tailored ImmunoCAPs was not correlated to allergic symptoms. We recommend the application of CCD tools to assess the relevance of individual wood sensitization. Cite this as: S. Kespohl, V. Schlünssen, G. Jacobsen, I. Schaumburg, S. Maryska, U. Meurer, T. Brüning, T. Sigsgaard and M. Raulf‐Heimsoth, Clinical & Experimental Allergy, 2010 (40) 1099–1106.     

Purified natural and recombinant Fel d 1 and cat albumin in in vitro diagnostics for cat allergy

BACKGROUND: Current diagnostics and therapeutics for cat allergy are based on cat epithelial extracts originating from highly variable source materials. This gives rise to several problems: variability of allergen composition, contamination with house dust mite allergens, and potential transfer of pathogenic agents. OBJECTIVE: The aim of this study was to investigate the feasibility of replacing cat epithelial extracts with purified natural or recombinant allergens. METHODS: Sera (n = 509) were selected on the basis of a positive cat RAST result and tested in a RAST for IgE reactivity to purified Fel d 1, cat albumin (CA), or both. The analysis was performed with both natural and recombinant allergens. In addition, some sera were further analyzed by means of immunoblotting. A serum pool was used for cat RAST inhibition with purified natural and recombinant allergens as inhibitors. RESULTS: Natural and recombinant Fel d 1 caused very similar results: 94.1% and 96.1% positive test results, respectively. In general, the negative sera were low responders to cat extract. The addition of CA (16.7% positive sera) resulted in a decrease in the number of discrepencies between purified allergens and whole extract to 2.8%. Only for 2% of all sera, sensitization to cat was largely explained by IgE reactivity to CA. IgE reactivity to Fel d 1 accounts for 88% of the total IgE response to cat allergens, as was demonstrated by RAST, with Fel d 1 concentrations nearing saturation. Recombinant Fel d 1 performed equally well in the RAST analysis. Recombinant CA was succesfully expressed in the yeast Pichia pastoris, and its immune reactivity closely resembled that of its natural counterpart. CONCLUSION: Natural and recombinant Fel d 1 and CA are good candidates for replacing ill-defined cat dander extracts in diagnostics for cat allergy. Although CA is not essential for the vast majority of cat-sensitized patients, some subjects are selectively sensitized to this serum protein.     

Occupational allergy in laboratory workers caused by the African migratory grasshopper Locusta migratoria

BACKGROUND: Recent reports of fatal asthma cases associated with swarms of locusts affecting African countries have highlighted the importance of this insect in causing asthma morbidity and mortality. However, only limited information is available about the allergic health outcomes such as asthma and its determinants in exposed individuals. In this study, workers exposed to the African migratory locust Locusta migratoria were evaluated for allergic health outcomes as well as the nature of the offending allergens. METHODS: Ten scientists and technicians exposed to locusts in a laboratory were investigated for locust-related allergy using questionnaires and immunological tests. The presence of allergy was determined by quantification of specific IgE and IgG to L. migratoria using the UniCAP system and via skin-prick testing (SPT). The allergens were characterized by Western blot and ImmunoCAP inhibition assays. RESULTS: Six of the 10 workers experienced symptoms ranging from urticaria and rhinoconjuctivitis to asthma. Seven individuals demonstrated sensitivity on SPT and five had specific IgE antibodies to L. migratoria. Significant cross-reactivity was demonstrated for allergens in the locust faeces, body and wings but not to cockroach allergens. Novel allergens with molecular weights of approximately 70 kDa were identified in locust wings, which are distinctly different from other known allergen sources from locusts. CONCLUSION: Exposure to L. migratoria allergens is a potential sensitizer in exposed individuals. Raised levels of locust-specific IgE can be readily quantified. The wings of this insect species have been identified as a novel allergen source.