Occupational wood-dust sensitivity from Euonymus europaeus (spindle tree) and investigation of cross reactivity between E.e. wood and Artemisia vulgaris pollen (mugwort)

A 44-year-old goldsmith suffered from rhinitis and conjunctivitis after having worked with wood dust from Euonymus europaeus (E.e.) for 15 years. The material was used for drying pieces of jewelry. Very strong reactions could be seen after friction test, scratch test and nasal challenge using wood dust of E.e. RAST-class 3 could be measured with the serum of this patient using E.e. wood and Artemisia vulgaris (A.v. pollen) allergen disks. RAST-inhibition, western-blot (WB) and immunoprint (IP) indicated common allergens in extracts of E.e. wood and A.v. pollen of different degree. In addition this study indicated that subjects suffering from A.v. pollen allergy also show sensitization to E.e. wood since in 22 of 37 A.v. pollen allergies A.v. (RAST class 2-4) IgE-antibodies could be seen. The present case probably demonstrates for the first time an IgE-mediated type I allergy to E.e. wood.     

Allergy to foods in patients monosensitized to Artemisia pollen

It is known that patients with pollinosis may display clinical characteristics caused by allergy to certain fruits and vegetables, but subjects allergic to Artemisia seem to show particularly peculiar characteristics. The clinical features of 84 patients with rhinitis, asthma, urticaria, and/or anaphylaxis whose inhalant allergy was exclusively to Artemisia vulgaris were studied and compared with a control group of 50 patients monosensitized to grass pollen. The mean age for the beginning of symptoms was 30.2 years, and this was higher than in the control group ( P <0.05). We found the main incidence to be in women (70.2%). Some 42.3% had family history of atopia, lower than in the control group ( P <0.05), while the prevalence of asthma and urticaria was significantly higher ( P <0.05). Food hypersensitivity was reported by 23 patients (27.3%) allergic to Artemisia. The foods responsible (with respective numbers of cases) were honey (14), sunflower seeds (11), camomile (four), pistachio (three), hazelnut (two), lettuce (two), pollen (two), beer (two), almond (one), peanut (one), other nuts (one), carrot (one), and apple (one). None of the patients monosensitized to grass had food allergy. CAP inhibition experiments were carried out on a single patient. Results showed the existence of common antigenic epitopes in pistachio and Artemisia pollen for this patient. We concluded that mugwort hay fever can be associated with the Compositae family of foods, but that it is not normally associated with other foods.     

Assessment of cross-reactivity in patients allergic to birch pollen by immunoblotting

Cross-reactivity related to birch pollynosis and ingestion of certain food poses a severe clinical and diagnostic problem. Sera were taken from 21 adult patients allergic to birch pollen with symptoms after ingestion of apples, carrots and celeries, and seven control subjects allergic to birch pollen only. Concentrations of allergen-specific IgE against allergens of birch pollen, apple, carrot and celery were measured with enzyme immunoassay, fluorimetric enzyme-linked immunoassay and immunoblotting. Immunoblotting technique may serve as a valuable diagnostic tool for birch pollen associated cross-reactivity.     

Heterogeneity of grass pollen allergens (Dactylis glomerata) recognized by IgE antibodies in human patients sera by a new nitrocellulose immunoprint technique

A new nitrocellulose immunoprint technique has been developed to detect specific antigens or/and allergens present among a heterogeneous solution such as a water-soluble crude extract of a grass pollen (Dactylis glomerata). The antigens are separated by isoelectric focusing (IEF) in an agarose gel and characterized by their isoelectric point (pI). These antigens are transferred and immobilized on a nitrocellulose sheet. They are recognized by the binding of specific antibodies contained in an unfractionated serum to be studied. Finally, the binding of these antibodies is visualized by species- or/and class-specific antibodies themselves labeled by an enzyme or by radioactivity. So one can detect the allergens recognized by the specific serum IgE antibodies and also the other antigens recognized by specific IgG, IgA or IgM antibodies.     

Allergy to fruits and vegetables in pollen‐sensitive patients: Allergen characterization by IgE immunoblotting and peroxidase staining

Allergies to several plant foods, i.e. apples, nuts, stone fruits, celery and spices, are highly associated with pollen allergies. The observed crossreactivities are due to structural similarities between food and pollen allergens. Using horseradish peroxidase (HRP) as the marker enzyme we have further developed and optimized a sensitive and specific immunoblotting procedure for the detection of human IgE antibodies specific to food and pollen proteins separated by SDS‐PAGE and immobilized on nitrocellulose blots. Our optimization studies involved four colour substrates and six buffer systems. The best results were obtained when 0.3% Tween 20 and no protein was used for membrane blocking, whereas blocking with proteins yielded high backgrounds. Immuno‐ detection amplification was accomplished by the following incubation steps: (a) sample (human serum); (b) secondary antibody; (c) biotinylated tertiary antibody; and (d) streptavidin‐HRP. Staining was performed with 3,3',5,5'‐tetramethylbenzidine which is an Ames test‐negative, alternative substrate for HRP. The quality of several commercially available anti‐IgE antibodies was examined. For some of these reagents very high non‐specific binding to food and pollen proteins occurred. The application of our method to apple and birch pollen allergen characterization is described. Results of IgE‐ and IgG‐immunoblotting and immuno‐detection of allergens following two‐dimensional‐ electrophoresis, as well as cross‐reactivity studies by means of immunoblot inhibition, are presented.     

Identification of canary grass (Phalaris aquatica) pollen allergens by immunoblotting: IgE and IgG antibody-binding studies

The pollen of canary grass, which was introduced as a pasture grass from Europe, is a major allergen in the external environment of southern Australia. Seventeen allergenic fractions of canary grass pollen, ranging in mol. mass from 14 to 100 kDa. have been identified by immunoblotting, using IgE antibodies from sera of 24/30 grass-pollen-allergic subjects. The highest frequency of IgE binding (77%) was to a major 34-kDa fraction (tentatively designated Pha a I). This protein bas been partially purified and identified as a group I allergen by immunodepletion experiments, with partially purified Lol p I (from rye-grass pollen), atopic serum, and Lol p I-specific MAb. In addition, microsequencing of the N -terminus of Pha a I showed an amino acid sequence identical to Lol p I. In a separate study. IgE binding to Western blots of Pha a I, Lol p I. and Cyn d I was investigated in 24 sera and found to occur in 19/24. 18/24, and 9/24. respectively. IgE binding to ail three major allergens, and to both Pha a I and Lol p I, occurred in 8/24 sera. Our findings suggest that while tbe N -terminal sequence of Pha a I is identical to Lol p I, there may be specific allergenic epitopes exclusive to this allergen that are important for allergenicity in southern Australia.     

The influence of a residual group in low-molecular-weight allergoids of Artemisia vulgaris pollen on their allergenicity,IgE- and IgG-binding properties

BACKGROUND: Reaction of epsilon-amino groups of lysine with potassium cyanate, maleic, or succinic anhydride leads to allergoids of low molecular weight. No study has been performed to compare their properties and investigate the influence of a residual group on allergenicity and human IgE- and IgG-binding of these derivatives. METHODS: Allergoids of a pollen extract of Artemisia vulgaris were obtained by means of potassium cyanate, and succinic and maleic anhydride. Biochemical properties were investigated by determination of amino groups, enzyme activity, isoelectric focusing IEF and SDS-PAGE. IgE- and IgG-binding was determined using immunoblots and ELISA inhibition. Allergenicity was investigated by skin prick tests (SPT) on a group of 52 patients, of which 6 were control subjects, 30 were patients with no previous immunotherapy (IT), and 16 were patients undergoing immunotherapy. RESULTS: The same degree of amino-group modification (more than 85%), residual enzyme activity (less then 15%), IEF, and SDS-PAGE pattern were noted. In the immunoblots of IgE-binding, there was more pronounced reduction in the succinyl and maleyl derivatives than in the carbamyl one. IgG-binding was less affected by carbamylation than by acid anhydride modification. The SPT showed that the succinylated derivative had the most reduced allergenicity (98% showed a reduced wheal diameter when tested with the succinyl derivative, 87% with the maleyl allergoid, and 83% with the carbamyl allergoid). The most significant difference among allergoids could be seen in the group of patients with high skin reactivity (83% of patients showed no reaction to the succinyl derivative when compared to the value of 28% for the carbamyl derivative or 22% for the maleyl derivative). CONCLUSIONS: According to our results, all three modification procedures yielded allergoids with a similar extent of modification. No single biochemical parameter investigated in the study could predict the degree of reduced allergenicity in vivo. The most reduced allergenicity was seen in the succinyl derivative while the preservation of IgG binding epitopes was of the highest degree for the carbamyl derivative.     

IgE reactivity and cross-reactivity of Japanese monkeys (Macaca fuscata) to Japanese cedar (Cryptomeria japonica) and cypress (Chamaecyparis obtusa) pollen allergens

BACKGROUND: The natural occurrence of Japanese cedar (Cryptomeria japonica, CJ) pollinosis has been reported in Japanese monkeys (Macaca fuscata). However, the reactivity to Japanese cypress (Chamaecyparis obtusa, CO) pollen allergens in these monkeys has not yet been reported. OBJECTIVES: The present study was designed to investigate the reactivity to CO pollen allergens in monkeys sensitized to CJ pollen allergens. METHODS: Serum samples from 40 monkeys naturally sensitized to CJ pollen allergens were collected from four troops. We measured the specific IgE to CO pollen allergens and examined the reactivity to the allergens by intradermal test. Cross-reactivity between CJ and CO pollen allergens was examined by ELISA inhibition method. Furthermore, we examined the sensitivity to the allergens by histamine release assay from leucocytes. RESULTS: All 40 monkeys had specific IgE to crude and purified major allergens (Cha o 1) of CO pollen. The monkeys showed a positive reaction to CO pollen allergens in the intradermal test. Allergenic cross-reactivity between Cha o 1 and Cry j 1 (a major allergen in CJ pollen) was also observed. Specific histamine release to both the major allergens was noted in two monkeys with CJ pollinosis. CONCLUSION: Japanese monkeys sensitized to Japanese cedar pollen allergens also demonstrate reactivity to Japanese cypress pollen allergens.     

Specific IgE determinations to crude and boiled lentil (Lens culinaris) extracts in lentil-sensitive children and controls

BACKGROUND: The aims of this study were to evaluate the allergenicity of boiled and crude lentil extracts and to compare specific IgE binding in tolerant and nontolerant lentil-allergic children. METHODS: Thirty-eight children were studied and divided into three groups. Group I comprised 24 children with a positive open oral challenge, or a convincing history of anaphylaxis after the ingestion of lentils; group II comprised nine children with a history of allergic reactions in the past, but currently tolerant of lentils; and group III comprised five children allergic to other legumes, but always tolerant of the ingestion of lentils. Specific IgE determinations and ELISA inhibitions were performed with the crude and boiled lentil extracts. The allergenic profile of both extracts was evaluated by SDS-PAGE and immunoblot. RESULTS: Mean specific IgE levels in group I were significantly higher than in groups II and III. The heating process caused a significant decrease in specific IgE binding. However, IgE-inhibition studies showed that the boiled lentil extract had a greater inhibitory capacity than the crude extract. Immunoblots revealed no important differences in IgE-binding patterns between the two extracts. Multiple allergens were detected in a wide range of molecular masses. CONCLUSIONS: Boiled lentil extracts maintain strong allergenicity. Patients who have developed tolerance of lentil ingestion have lower specific IgE levels than symptomatic patients.     

The allergen profile of ash (Fraxinus excelsior) pollen: cross-reactivity with allergens from various plant species

BACKGROUND: Ash, a wind-pollinated tree belonging to the family Oleaceae, is distributed world-wide and has been suggested as a potent allergen source in spring time. OBJECTIVE: The aim of this study was to determine the profile of allergen components in ash pollen in order to refine diagnosis and therapy for patients with sensitivity to ash pollen METHODS: The IgE reactivity profile of 40 ash pollen-allergic patients was determined by immunoblotting. Antibodies raised to purified pollen allergens from tree and grass pollens were used to identify cross-reactive structures in ash pollen extract. IgE immunoblot inhibition studies were performed with recombinant and natural pollen allergens to characterize ash pollen allergens and to determine the degree of cross-reactivity between pollen allergens from ash, olive, birch, grasses and weeds. RESULTS: The allergen profile of ash pollen comprises Fra e 1, a major allergen related to the major olive allergen, Ole e 1, and to group 11 grass pollen allergens, the panallergen profilin, a two EF-hand calcium-binding protein, a pectinesterase-like molecule and an allergen sharing epitopes with group 4 grass pollen allergens. Thus, the relevant allergens of ash are primarily allergens that share epitopes with pollen allergens from other tree, grass and weed species. CONCLUSIONS: Allergic symptoms to ash pollen can be the consequence of sensitization to cross-reactive allergens from other sources. The fact that ash pollen-allergic patients can be discriminated on the basis of their specific IgE reactivity profile to highly or moderately cross-reactive allergens has implications for the selection of appropriate forms of treatment.     

IgE and IgG antibodies of patients with allergy to birch pollen as tools to define the allergen profile of Betula verrucosa*

IgE and IgG antibody response to birch pollen antigens were studied by means of immunoblotting experiments testing 58 sera from patients with Type I allergy to birch pollen. 56/58 patients showed IgE antibodies reactive with Bet v I, a 17 kilodalton (kD) pollen protein. 2D-electrophoresis/immunoblot revealed a heterogeneity of that protein. Ten spots (pH 4.9-5.9) could be detected, presumably representing differentially glycosylated isoallergens. In 33/58 patients, there was no evidence of IgE antibodies directed against allergens other than Bet v I. However, in 25/58 of patients' sera, 11 minor allergens (13, 15, 18, 27, 29, 32, 39, 44, 57, and 68 kD) with individual incidences from 1.7% to 17.2% were identified. All proteins were also recognized by the patients' IgG antibodies: in the case of Bet v I recognition was weak, whereas the IgG response to the minor allergens was pronounced. Sera from healthy individuals showed similar IgG antibody responses, but no IgG to the 15, 27, and 29 kD proteins. Our results suggest that IgG directed against minor allergens may function as trapping antibodies in healthy individuals. Too low or lacking amounts of anti-Bet v I IgG may facilitate an allergic reaction.     

Immunotherapy with partially purified and standardized tree pollen extracts. IV. Results from long-term (6-year) follow-up

The long-term effect of tree pollen extract immunotherapy was investigated 6 years after termination of the treatment. Subjective symptom evaluation of 36 patients 6 years after a 3-year period of immunotherapy showed that rhinitis and asthma symptoms remained at the improved level reached just after termination of the treatment. Some 86% of the rhinitis patients and 68% of the asthma patients maintained improvement. None of the rhinitis patients developed asthma in the study period. Skin prick tests reflected the outcome of the subjective symptom assessment. The skin sensitivity of the patients decreased significantly during immunotherapy, and the skin reactions 6 years after specific immunotherapy were still significantly lower than the pretreatment levels. Total IgE and birch-specific IgE levels were constant throughout the study period, and both the affinity and epitope specificity of the IgE antibodies of the patients were the same before, during, and 6 years after treatment. In conclusion, specific immunotherapy reduces symptoms in patients suffering from rhinitis and asthma, and the effect is maintained 6 years after termination of the treatment. Specific immunotherapy seems to prevent long-term development of asthma in rhinitis patients. IgE measurements do not reflect the overall status of the patients.     

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.     

Effects of IL-4 and IL-13 on total and allergen specific IgE production by cultured PBMC from allergic patients determined with recombinant pollen allergens

Background: Interleukin (IL)-4 and IL-13 have been shown to be potent switch factors for IgE synthesis in human B cells. Objective: In this study we investigated the effects of recombinant human IL-4 and IL-13 on total and allergen specific IgE synthesis by peripheral blood inononuclear colls (PBMC) from pollen allergic patients and healthy control individuals. Methods: Peripheral blood mononuclear cells (PBMC) from allergic patients were investigated for their capacity to produce allergen specific IgE in vitro. Total protein extracts from birch pollen and timothy grass pollen as well as purified recombinant birch pollen allergens, Bet v I, birch profiling (Bet v II) and recombinant timothy grass pollen allergens. Phi p I, Phi p II, and Phi p V were used to measure specific IgE-antibody synthesis in cell culture supernatants by IgE-immunoblot and ELISA. Reults PBMC obtained from allergic patients spontaneously secreted allergen specific IgE in the culture supernatants. Addition of Interleukin 4, Interleukin 13 and anti-CD40 antibody to the cultures alone or in combinations significantly induced total IgE production whereas allergen specific IgE production was not affected. Conclusion: Our results indicate that the peripheral blood of allergic individuals contains long lived allergen specific B cells which have already switched to IgE production and which are not sensitive to IL-4 and IL-13 treatment. These results may have implications on attempts to use cytokines or cytokine antagonists in therapy of Type I allergy.     

Allergens in pollen from mugwort (Artemisia vulgaris L.). II. Characterization of a crude and a partly purified extract of mugwort pollen with particular emphasis on the glycoprotein allergen Ag7

A crude and a partly purified extract of mugwort pollen were characterized with particular emphasis on the glycoprotein allergen Ag7. Crossed immunoaffinoelectrophoresis with immobilized Con A in the intermediate gel demonstrated binding of Ag7 to this lectin, indicating that Ag7 contains terminal alpha-D-mannopyranosyl and/or alpha-D-glucopyranosyl residues. Crossed immunoaffinoelectrophoresis with free Con A in the first-dimension gel demonstrated microheterogeneity in the carbohydrate moiety of the allergen. Crossed radioimmunoelectrophoresis analysis using sera from 26 mugwort-allergic patients indicated that Ag7 is an important allergen in mugwort pollen. Heat stability experiments demonstrated the presence of at least three heat-resistant allergens, one of these being Ag7. Crossed immunoelectrofocusing indicated a pI value for Ag7 of 4.3.     

Evaluation of IgE antibodies to recombinant pollen allergens (Phl p 1, Phl p 2, and Phl p 5) in a random sample of patients with specific IgE to Phleum pratense

BACKGROUND: We measured specific IgE levels against the recombinant allergens (RAs) rPhl p 1, rPhl p 2, and rPhl p 5 in patients allergic to grass pollen, and examined the existence of different patterns of IgE production to RAs. The seasonal variations of IgE levels to rPhl p 1, rPhl p 2, and rPhl p 5 were considered, too. METHODS: Blood was taken from 276 consecutive patients with allergy to grass pollen diagnosed by patient history and skin prick testing. Total and specific serum IgE was measured by the immunoenzymatic CAP FEIA System. Eosinophil cationic protein (ECP) and myeloperoxidase (MPO) were assessed by radioimmunoassay according to the instructions of the manufacturers. RESULTS: We observed eight different patterns of IgE production to rPhl p 1, rPhl p 2, and rPhl p 5 in patients with specific IgE to timothy grass. A significant difference between the values of IgE levels to timothy and the sum of each level of specific IgE to individual RAs was found (P = 0.039, Wilcoxon matched pairs test) in the whole population (n = 276 subjects). In four subgroups of patients, the sum of each level of specific IgE to individual RAs was equal to the levels of specific IgE to timothy grass extract. In one subgroup, the sum of IgE to RAs was lower than the levels of IgE to the natural counterpart (P = 0.013). A lack of subjects in two subgroups did not permit comparison at all. Finally, three subjects with specific IgE to timothy did not show specific IgE to RAs. Out of 276 patients, blood was taken from two different groups of subjects at different time points: November-January and May-July, respectively. The median values were as follows: total IgE = 139 kU/l, IgE to timothy = 10.2 kUA/l; IgE to rPhl p 1 = 3.6 kUA/l, to rPhl p 2 = <0.35 kUA/l, and to rPhl p 5 = 1.1 kUA/l; ECP = 8.25 microg/l; MPO = 303.08 microg/l (before exposure to grass pollen); total IgE = 159 kU/l, IgE to timothy = 57.2 kUA/l; IgE to rPhl p 1 = 22.1 kUA/l, to rPhl p 2 = 5.9 kUA/l, and to rPhl p 5 = 3.9 kUA/l; ECP = 16.21 microg/l; MPO = 413.09 microg/l (during the pollen season). There were significant variations of specific IgE levels between the patients exposed to pollen and the unexposed patients. Moreover, there were statistical differences in the IgE, ECP, and MPO levels in sera before and during the pollen season P<0.035, P<0.017, and P<0.0062, respectively. CONCLUSIONS: The results suggest that RAs allow establishment of the patient's IgE-reactivity profile, encourage future research, and encourage manufacturers to produce further RAs for precise diagnosis and substantially improved immunotherapy injection of only those allergens against which significant amounts of specific IgE are produced.     

Evaluation of immunotherapy-induced changes in specific IgE, IgG and IgG subclasses in birch pollen allergic patients by means of immunoblotting

Sera from 27 birch pollen-allergic patients who had undergone hyposensitization treatment for 22-41 months were studied by immunoblotting before and after therapy, whereby the levels of IgE, IgG and IgG1-4 antibodies directed against the major allergen Bet v I and minor allergens of birch pollen were monitored. The clinical benefit of immunotherapy (IT) was evaluated using a symptom specific questionnaire. In patients with good clinical response (responders, n = 18), as defined by improvement of symptoms, anti-Bet v I IgE antibodies were found to decrease in 10/18 patients (55.5%), whereas in 6/18 (33.3%) no change and in two cases (11.2%) an increase of specific IgE was observed. In the group of patients with unsatisfactory clinical outcome (non-responders, n = 9), 3/9 patients (33.3%) showed a decrease, 3/9 (33.3%) no change and 3/9 (33.3%) an increase in levels of IgE antibodies directed against Bet v I. In the case of minor allergens, 5/18 responders (27.7%) and 8/9 non-responders (88.8%) showed specific IgE before IT. In the responder group, no increase of specific IgE could be observed after IT. In non-responders, however, an increase of IgE directed against minor allergens was seen in 3/9 patients (33.3%). In all patients, regardless of therapeutical success, IT-induced elevated levels of specific IgG, IgG1 and in particular IgG4 directed against Bet v I were found. Regarding minor allergens, a heterogeneous pattern of IgG responses without significant correlation to clinical benefit was observed. Our results indicate that changes in IgG reactivity patterns against Bet v I and minor allergens, as shown by the immunoblot technique, did not correlate with good or bad clinical outcome.     

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.