Analysis of antigenic determinants shared by two different allergens recognized by human T cells: house dust mite (Dermatophagoides pteronyssinus) and chironomid midge (Chironomus yoshimatsui)

To analyse the cross-reactivity of T-cell-mediated immunity between Dermatophagoides pteronyssinus (Dp) and Chironomus yoshimatsui (Cy), the most common allergens in Japan, we established antigen-specific human T-cell lines and clones. Some but not all of the Cy-induced T-cell lines showed a significant proliferative response not only to Cy, but also to Dp. No T-cell line responded to other unrelated antigens. When we stimulated the Dp-induced T-cell clones with Cy, 3 of the 40 clones (7.5%) showed a significant proliferation, and 2 of the 3 clones produced interleukin-4 and interferon-gamma, indicating their helper function. Cross-reactivity was diminished significantly after the absorption of Dp antigen in an anti-Cy affinity column. The cross-reactive epitopes were thought to be expressed on the Dp molecule of 45-53 kD. The presence of helper T cells reactive to both allergens suggests a possibility that this cross-reactivity might be involved in part in the high incidence of allergy to the 2 major allergens.     

Par j 1 and Par j 2, the major allergens from Parietaria judaica pollen, have similar immunoglobulin E epitopes

BACKGROUND: Parietaria judaica is the main cause of allergy in Mediterranean countries. The major allergens from P. judaica pollen, Par j 1 and Par j 2, have amino acid sequence identity of 45% and contain eight cysteine residues involved in disulphide bonds that compact the structure. OBJECTIVE: The aim of the study was to identify IgE-binding epitopes on Par j 1 and Par j 2, the major allergens from P. judaica pollen and correlate them with the three-dimensional structure of the proteins. METHODS: Overlapping peptides representing the complete length of Par j 1 and Par j 2 were synthesized on a cellulose-derivatized membrane. Sera from 17 P. judaica-allergenic patients were used to identify IgE-binding epitopes. Homology modelling of the three dimensional structure of both allergens was generated using the Swiss-Model software on the basis of previously reported crystal structures. RESULTS: Five and eight IgE-binding epitopes were identified on Par j 1 and Par j 2 allergens, respectively. Both proteins belonged to the non-specific lipid transfer proteins (ns-LTP) family and therefore a three-dimensional model of both allergens was constructed on the basis of the maize ns-LTP crystal structure. Par j 1 and Par j 2 allergens have three similar allergenic epitopes with high homology and identical conformation. CONCLUSION: Three similar IgE-epitopes of major allergens from P. judaica have been described. They could be good candidates for designing of IgE haptens as therapeutic agents with reduced anaphylactic side-effects or for developing hypoallergenic variants of these major allergens.     

Fagales pollen sensitization in a birch-free area: a respiratory cohort survey using Fagales pollen extracts and birch recombinant allergens (rBet v 1, rBet v 2, rBet v 4)

BACKGROUND: Birch allergy is one of the most common pollinosis in areas where exposure to high levels of birch pollen is common. Little is known about birch sensitivity in areas without birch pollen exposure and reactivity to birch-related species within the Fagales order. OBJECTIVE: the aim was to evaluate Fagales reactivity within a population not exposed to birch pollen using epidemiological, diagnostic, and laboratory approaches by means of extracts and allergenic molecules. METHODS: A cohort of 5335 respiratory allergic patients was screened by means of skin testing birch, hazel, and oak pollen extracts. Patients were from a birch-free area, but exposed to other Fagales pollen species. A subset of patients was from an intensively cultivated hazel area. A sample of the Fagales allergic population was tested with other Fagales pollen extract (alder, hornbeam, beech, chestnut) and with apple and hazelnut. IgE detection was performed with birch, hazel, oak, apple, and hazelnut extracts, and with Bet v 1, Bet v 2, Bet v 4, and bromelain. IgE immunoblots were performed using birch and hazel extracts. Epidemiological, clinical, and laboratory data were analysed by stratifying the allergic population. RESULTS: Twenty-five percent of the pollen allergic cohort was skin test positive to at least one of the three Fagales species. Combined reactivity to the three species was recorded in 80% of this cohort. Isolated hazel pollen reactivity was recorded in 13.5% of the Fagales allergic patients. Sixty-six percent of these subjects were from the intensively cultivated hazel area. Reactivity to apple and hazelnut was detected by skin test (40%) and IgE reactivity (60%), but only 19% of the positive patients reported symptoms related to at least one of the two foods. Reactivity to Bet v 1 was recorded in 84% of the birch/hazel/oak co-reactivity group, and in 28% of the subjects with the same co-reactivity, but associating a multiple pollen sensitization. IgE to Bet v 2 (50%) and Bet v 4 (23%) panallergens were recorded positive in the latter subset. Bet v 1 prevalence ranged between 48% and 21% among subgroups of patients coming from different areas. Furthermore, an IgE reactivity to hazel-restricted allergenic components was detected among subjects coming from the same area and having a hazel isolated reactivity. CONCLUSION: Fagales allergy can be found in birch-free areas caused by the exposure to other Fagales species. Birch allergens can be useful for mimicking the allergenic extract, but are also the exclusive tools for a fine diagnostic and epidemiological approach to Fagales pollen allergy. Allergenic molecules from the hazel family will increase the panel of available reagents for the molecule-based approach to allergy diagnosis and therapy.     

Measurement of IgE antibodies against purified grass pollen allergens (Lol p 1, 2, 3 and 5) during immunotherapy

Background IgE titres tend to rise early after the start of immunotherapy, followed by a decline to pre-immunotherapy levels or lower. Objectives We were interested to ktiow whether the early increase in IgE antibodies includes new specificities of IgE, and whether these responses persist. Methods Sera of 64 patients undergoing grass pollen immunotherapy were tested for IgE against four purified grass pollen allergens: Lol p 1. 2, 3, and 5. At least two serum samples were taken, one before the start of therapy and one between 5 and 18 months after the first immunization (mean: 10 months). Results The mean IgE responses to Lol p 1, 2 and 3 showed a moderate but not significant increase. In contrast, the mean IgE response to Lol p 5 showed a significant decrease of >30%. IgE against total Lolium perenne pollen extract moderately increased (>20%), showing that a RAST for total pollen is not always indicative for the development of IgE against its major allergens. For >40% of the patients it was found that IgE against one or more of the four allergens increased, while IgE against the remaining allergen(s) decreased. Eor 10 sera the ratio of IgE titres against at least two allergens changed by at least a factor of 5. The changes in specific IgE also included conversions from negative (< 0.1 RU) to positive (0.6 to 5.0 RU) for five patients. For two patients, the induction of these ‘new’ IgE antibodies against major allergens was shown to result in a response that was persistent over several years. Conclusion Although active induction of new IgE specificities by immunotherapy was not really proven, the observations in this study indicate that monitoring of IgE against purified (major) allergens is necessary to evaluate changes in specific IgE in a reliable way.     

Distribution of dust-mite allergens (Lep d 2, Der p 1, Der f 1, Der 2) in pig-farming environments and sensitization of the respective farmers

BACKGROUND: The aim of the present study was to determine the distribution of mite allergens in pig-farming environments in comparison to urban homes and the relationship between exposure to mite allergens and sensitization to the respective allergens in 100 pig farmers with work-related respiratory symptoms. METHODS: The concentration of storage mite (Lep d 2) and house-dust-mite (Der p 1, Der f 1, and Der 2) allergens in dust collected from five different sampling sites (floor, wall, grain mill, transit area between confinement house and farmer's kitchen, and farmers' mattresses) was studied in relationship to the respective sensitization rates. Allergen concentrations in the mattresses were compared to those determined in mattresses from 22 urban dwellers. RESULTS: Median concentrations of Der p 1 and Der 2 in the mattresses of the farmers were significantly higher than in the urban dwellers' samples (53.4 microg/g dust vs 1.05 microg/g dust, P=0.001; 19.6 microg/g dust vs 2.2 microg/g dust, P<0.0001, respectively). Allergen concentrations in the transit areas were strongly related to bedroom exposure. In a multiple logistic regression model, a weak but significant relationship between Der p 1 exposure and sensitization to Der p 1 was found. Despite these findings, the prevalence of sensitization to mite allergens in the farmers (18%) was comparable to the prevalence in the general population. CONCLUSIONS: Allergen exposure at the workplace is strongly related to the concentration of allergens in farmers' beds. Exposure to domestic mite allergens should be taken into account when assessing occupational exposure to allergens and the respiratory health of farmers.     

Characterization of the T cell response to the major hazelnut allergen, Cor a 1.04: evidence for a relevant T cell epitope not cross-reactive with homologous pollen allergens

BACKGROUND: IgE antibodies specific for the major birch-pollen allergen, Bet v 1, cross-react with homologous allergens in particular foods, e.g. apples, carrots and hazelnuts. In a high number of tree pollen-allergic individuals, this cross-reactivity causes clinical symptoms, commonly known as the 'birch-fruit-syndrome'. OBJECTIVE: To characterize the T cell response to the Bet v 1-related major allergen in hazelnuts, Cor a 1.04, and its cellular cross-reactivity with Bet v 1 and the homologous hazel pollen allergen, Cor a 1. METHODS: Using recombinant Cor a 1.04, T cell lines (TCL) and T cell clones (TCC) were established from peripheral blood mononuclear cells of tree pollen-allergic patients with associated food allergy. T cell epitopes were determined using overlapping synthetic peptides in Cor a 1.04-reactive TCL and TCC. In parallel, reactivity to Bet v 1 and Cor a 1 was tested. RESULTS: In total, 20 distinct T cell epitopes on the hazelnut allergen were identified. Several Cor a 1.04-specific TCL and TCC reacted with pollen allergens albeit less pronounced than with the hazelnut allergen. Several Cor a 1.04-specific TCC did not react with pollen allergens. Interestingly, these clones were found to react with the Bet v 1-related major allergen in carrots, Dau c 1. The cellular cross-reactivity between both food allergens could be associated with the most frequently recognized T cell epitope of Cor a 1.04, Cor a 1.04(142-153). CONCLUSIONS: The major hazelnut allergen cross-reacts with the major allergens of birch and hazel pollen but apparently contains a relevant T cell epitope not shared with pollen allergens. Our finding may have important implications for the specific immunotherapy of tree pollen-allergic patients suffering from concomitant hazelnut allergy.     

Domestic allergens in public places II: dog (Can f 1) and cockroach (Bla g 2) allergens in dust and mite, cat, dog and cockroach allergens in the air in public buildings

Background Sensitization and exposure to indoor allergens are the major risk factors for asthma. It is possible that significant exposure to domestic allergens occurs outside the home. Objectives To investigate the levels of Can f 1 and Bla g 2 in the dust from carpeted floors and upholstered seats in public buildings and public transport and the airborne concentrations of Der p 1, Fel d 1, Can f 1 and Bla g 2 in schools and offices. Methods Can f 1 and Bla g 2 were measured in the dust collected by vacuuming a I m² area of carpet, as well as upholstered seats in five schools, six hotels, four cinemas, six pubs, three buses and two trains. Dust was also collected from the bedroom carpet, living room carpet, mattress and sofa in 20 homes with and 20 homes without a dog in the same area. Personal airborne sampling (2 L/min) was conducted for 8 h in offices (n= 16) and classrooms (n= 9). In addition, airborne samples in schools were collected using a high volume pump (60 L/min) for 1 h in three classrooms immediately after the children vacated the school. Can f 1, Bla g 2, Der p 1 and Fel d 1 were assayed using a two–site monoclonal antibody–based ELISA. Results Can f 1 was detected in all dust samples from public places, ranging from 0.2 to 52.5 μg/g, Significantly higher levels were found in upholstered scats (geometric mean – GM 9.4 μg/g) than in carpets (GM 1.5 μg/g; P < 0.001), and levels of Can f 1 > 10 μg/g were found in 40% of upholstered seats in public places. Can f 1 was significantly higher in upholstered seats in public places than in sofas in homes without a dog (GM 1.8 μg/g; P < 0.001). Detectable levels of Bla g 2 were found in all of the schools (GM 2.4 U/g, range 0.8–4.4 U/g). Bla g 2 concentration greater than 2U/g (provisional threshold level representing risk of sensitization) was measured in 65% of the classrooms sampled. Der p 1 and Bla g 2 were below the detection limit in all airborne samples. However, airborne Fel d 1 and Can f 1 were detected in schools and offices, albeit in low concentrations. Conclusions Upholstered seats from public places constitute a reservoir for the accumulation of dog allergen, and a source of exposure to Can f 1 inside public buildings or on public transport. Exposure to cockroach allergens in schools may be important for cockroach sensitized asthmatic children.     

Mite (Der p 1, Der f 1) and cat (Fel d 1) allergens in the homes of babies with a family history of allergy

Carpet and floor dust samples were collected in four different seasons, from 39 Swedish homes of babies with a family history of allergy. House-dust mite ( Der p 1, Der f 1 ) and cat ( Fel d 1 ) allergen contents were determined by mab ELISA, and the levels were related to various environmental factors. Both mite and cat antigens were detected in 94% of the samples and in all homes, but the levels were low ( Der p 1 , range 15 ng–1944 ng/g fine dust; Der f 1 , range 14 ng–264 ng/g of fine dust; Fel d 1 , range 16 ng–3120 ng/g fine dust). Mite-allergen levels were significantly higher ( P <0.001) in floor dust than in carpets, and D. pteronyssinus predominated. In contrast, the levels of cat antigen were significantly ( P <0.05) higher in carpets than in floor dust. There was no clear relation between mite-allergen levels and type of house, except that the higher values were found in homes with dampness problems. Cat-allergen levels were higher than total mite-allergen content, and the highest levels were found in homes with a cat ( P <0.05). Rather high concentrations of cat allergen were also found in homes without a cat, which may explain why cat sensitization is so common in Sweden. As the prevalence of house-dust mite sensitivity is increasing in Swedish children, and as the individual patient threshold for eliciting symptoms varies, we suggest that sensitization may possibly occur at a lower exposure level than generally accepted as risk level for sensitization (2 μg/g dust).     

Ash (Fraxinus excelsior)-pollen allergy in central Europe: specific role of pollen panallergens and the major allergen of ash pollen, Fra e 1

BACKGROUND: The role of ash (Fraxinus excelsior) pollen as a cause of spring pollinosis in central Europe has received little attention. It is not clear whether ash pollen is a primary cause of sensitization or whether it is implicated through cross-sensitization to other pollens. METHODS: Over a 22-month period, ash pollen was included in a screening series for inhalant allergies. Pollen data were documented from 1976 through 1999. The frequency of IgE-binding to the ash-specific allergen Fra e 1 and pollen panallergens, respectively, was compared by Western blot between mono- (n = 6), oligo- (n = 16), and polysensitized (n=25) patients. RESULTS: Of 5,416 consecutive patients sensitized to any pollen, 920 (17.6%) had a positive skin prick test to ash. Total pollen counts varied extensively between years (229-5,351) as did peak concentrations (23-837 grains/m3/24 h). Western blotting revealed Fra e 1 sensitization in 100% of monosensitized, 93% of oligosensitized, but only 44% of polysensitized patients. IgE against profilins (Fra e 2), Ca-binding proteins (Fra e 3), and carbohydrate epitopes in the three groups was found in 0/0/17%, 0/19/31%, and 32/72/60%, respectively. At least 50% of sera from patients with Fra e 1 sensitization did not bind with the protein in Western blots under reducing conditions. CONCLUSIONS: Ash pollen should be considered a relevant factor and distinct entity in spring pollinosis. In all, only 20% of positive skin tests to ash appear to result from cross-sensitization to pollen panallergens.     

峨嵋山发现蠓类二新种及一新纪录(双翅目:蠓科)

2010年9月中下旬在四川省峨眉县峨眉山(29.5°N,103.3°E)西南麓进行了挥网采集,获得蠓类2亚科10属11种,其中有2个新种:峨眉裸蠓(Atrichopogon emeiensis Deng,Liao et Yu sp.nov.)和李江柱蠓(Stilobezzia lijiangi Yu,Zhang et ...     

Skin test with a timothy grass (Phleum pratense) pollen extract vs. IgE to a timothy extract vs. IgE to rPhl p 1, rPhl p 2, nPhl p 4, rPhl p 5, rPhl p 6, rPhl p 7, rPhl p 11, and rPhl p 12: epidemiological and diagnostic data

BACKGROUND: The diagnostic approach to grass pollen allergy is now possible by detecting specific IgE to its allergenic components. OBJECTIVE: To compare the IgE reactivity to a timothy grass pollen extract with the IgE reactivity to eight allergenic components from the same source (Phl p 1, 2, 4, 5, 6, 7, 11, 12). Both were compared with the skin test reactivity to a timothy grass extract. METHODS: A population survey was carried out by means of the skin test to identify grass-allergic subjects, and to characterize them in terms of demographic and allergological parameters. Seven hundred and forty-nine sera were available for IgE detection to a timothy extract, to the recombinant Phl p 1, 2, 5, 6, 7, 11, 12, and to native Phl p 4 and bromelain. Results were stratified by means of demographic and allergy parameters. RESULTS: Ninety-five per cent of the sera had detectable IgE to the timothy extract. Prevalence of IgE reactivity increased from 86.8% to 93.3% as the number of combined reactive molecules rose from 2 to 8. Adjusted prevalences for each allergen were: rPhl p 1 = 83%, rPhl p 2 = 55%, nPhl p 4 = 70%, rPhl p 5 = 50%, rPhl p 6 = 44%, rPhl p 7 = 7%, rPhl p11 = 43%, rPhl p 12 = 15%. Isolated reactivity to rPhl p 1 was 6%, whereas it was negligible for the remaining molecules. IgE reactivity prevalence and mean values differed when patients were stratified on the basis of their associated pollen reactivity and their skin test reactivity grade. No differences were found when age, symptom type and duration were considered. Up to eight-fold higher IgE concentrations were found when the sum of IgE to molecules was compared with IgE to the extract. Testing for the IgE reactivity to the glycan of the native Phl p 4 allergen showed a possible interference with prevalence and value estimation. Higher prevalence values were found in previously immunotherapy-treated patients. CONCLUSIONS: The use of a complete panel of grass allergenic molecules can mimic the current use of allergenic extracts, but new relevant information, such as individual pattern of reactivity, adjusted prevalence, correct specific IgE concentration, can be achieved only by means of discrete allergenic molecules.     

IgE detection to α/β/γ‐gliadin and its clinical relevance in wheat‐dependent exercise‐induced anaphylaxis

Wheat‐dependent exercise‐induced anaphylaxis (WDEIA) is characterized by anaphylactic reactions after wheat ingestion and physical exercise. IgE antibodies to recombinant ω₅‐gliadin are detectable in a majority of WDEIA patients, but other wheat allergens may also play a role in elicitation of WDEIA. Here, we performed a comprehensive analysis of IgE reactivity to different wheat proteins in 17 patients with confirmed WDEIA by ImmunoCAP research prototypes and a semi‐quantitative microarray immunoassay with α/β/γ‐gliadin, high‐molecular‐weight (HMW) glutenin, alpha‐amylase inhibitor (AAI) dimer, and wheat lipid transfer protein (LTP). By ImmunoCAP, IgE to recombinant ω₅‐gliadin was detectable in 14/17 patients (82%), to α/β/γ‐gliadin in 82% including the three patients lacking IgE to ω₅‐gliadin, and to HMW glutenin in 59%. The microarray revealed specifically γ‐gliadin as the second most important allergen. These results demonstrate the additional diagnostic value of α/β‐ and γ‐gliadin in particular in ω₅‐gliadin‐negative patients in the diagnosis of WDEIA.