Grass pollen allergens: new developments

Allergy to hazelnut in adults: a two-step study

BACKGROUND

Although hazelnut consumption is very high in Turkey, the prevalence of hazelnut allergy is still unknown. This study's objective was to investigate the prevalence of hazelnut sensitisation and to verify its clinical importance using double-blind, placebo-controlled challenge (DBPCFC) in an adult population.

METHODS

Prick-to-prick skin tests were performed with fresh hazelnut in 904 patients admitted to the allergy department. Among the 904 subjects, 20 patients with a history of allergic reactions to hazelnut and/or positive skin tests were recalled for further evaluation. Specific IgE was measured in these subjects. Eleven (11/20) patients accepted to undergo DBPCFC with hazelnut.

RESULTS

Among the 904 individuals, the history of reactions to hazelnut was positive in 16 subjects (1.8%); prick-to-prick skin tests were positive in 13 (1.4%); prick tests with the commercial product were positive in nine (0.9%); and history plus skin tests were positive in 16 (1.8%). Specific IgE to hazelnut was positive in only three patients. DBPCFC was conducted in 11 subjects with a positivity rate of 63.6% (7/11). We observed six mild and one moderate systemic reactions during the DBPCFC. Among seven subjects with a positive DBPCFC, six (85.7%) had a history of hazelnut allergy, and five (71.4%) had both history and skin test positivity.

CONCLUSION

Skin test sensitisation to hazelnut was found to be 1.76% (16/904) which is similar to the sensitisation rate in previous reports. However, DBPCFC was positive in 63% of cases with a history of hazelnut allergy and/or positive skin tests in this study. These results indicate that the presence of history with a positive skin test can be suggestive of hazelnut allergy; however an oral food challenge is needed to confirm the diagnosis.

Global warming and allergy in Asia Minor

The earth is warming, and it is warming quickly. Epidemiological studies have demonstrated that global warming is correlated with the frequency of pollen-induced respiratory allergy and allergic diseases. There is a body of evidence suggesting that the prevalence of allergic diseases induced by pollens is increasing in developed countries, a trend that is also evident in the Mediterranean area. Because of its mild winters and sunny days with dry summers, the Mediterranean area is different from the areas of central and northern Europe. Classical examples of allergenic pollen-producing plants of the Mediterranean climate include Parietaria, Olea and Cupressaceae. Asia Minor is a Mediterranean region that connects Asia and Europe, and it includes considerable coastal areas. Gramineae pollens are the major cause of seasonal allergic rhinitis in Asia Minor, affecting 1.3-6.4 % of the population, in accordance with other European regions. This article emphasizes the importance of global climate change and anticipated increases in the prevalence and severity of allergic disease in Asia Minor, mediated through worsening air pollution and altered local and regional pollen production, from an otolaryngologic perspective.

Does regional pollen load affect the prevalence of clinical allergy to those pollen groups?

Objective:

To test the association between clinical allergic sensitisation to pollens and the profile and load of those pollens, in Ankara, Turkey.

Materials and methods:

Forty-three patients with seasonal allergic rhinitis were included. Clinical sensitisation to various pollens was compared with 10-year counts of the same pollens. The ratios of sensitisation to various pollen groups, and the association between clinical sensitisation and pollen load, were investigated.

Results:

Grass pollen allergy was the leading cause of seasonal allergic rhinitis, followed by tree pollen allergy. In Ankara, the most common type of airborne tree pollen was salicacea; however, the commonest clinical tree pollen allergies were due to the betulaceae and fagaceae families.

Conclusions:

Higher concentrations of airborne pollens may not always result in a higher prevalence of clinical allergy to those pollens.

Regional pollen load: effect on sensitisation and clinical presentation of seasonal allergic rhinitis in patients living in Ankara, Turkey

BACKGROUND

Although Gramineae pollens are the main reason for seasonal allergy in many parts of Europe, the influence of regional flora on sensitisation and symptoms has always been a topic of interest. The aim of this study was to document the sensitisation to pollens and to evaluate their clinical importance in patients with seasonal allergic rhinitis living in Ankara/central Anatolia.

METHODS

The study included those subjects with seasonal allergic rhinitis living in Ankara. Skin prick testing with a panel of common aeroallergens as well as grass, individual tree and weed pollens predominant in the region was performed. The patients were followed by symptom-medication scores during the same season in which regional pollens were also counted.

RESULTS

The final eligible study consisted of 54 subjects (F/M: 26/28; mean age: 29.4 years). Trees were the most common pollen source consisting of 95 % of the total amount, followed by grasses (3 %) and weeds (2 %). Sensitisation to Gramineae, to at least one weed; and to tree pollens were 100 %, 85.2 % and 94.4 %, respectively. The most common positive skin tests among tree pollens were to Oleaceae (59.2 %), Aesculus (57.4 %); and Tilia (42.5 %) despite low pollen counts. Chenopodiaceae (88 %) and Plantago (63 %) were the most sensitised weed pollens, with high pollen counts. All patients had significant symptoms during May and June.

CONCLUSION

Although Gramineae pollens seem to be major allergens for seasonal allergic rhinitis in Ankara, the particular role of tree pollens and weed pollens cannot be discarded on symptom development in sensitised patients.

Skin prick test results of child patients diagnosed with bronchial asthma

BACKGROUND

The pathogenesis of asthma is associated with both genetic and environmental factors. Allergen sensitization is an important risk factor in asthma development.

AIM

To evaluate sensitivity to allergens by using the skin prick test in patients with a diagnosis of bronchial asthma.

METHOD

Patients with a diagnosis of bronchial asthma followed-up at the Ministry of Health, Diskapi Children's Diseases Training and Research Hospital in Ankara (Turkey) between January 1995 and March 2000 were included. Sensitivity to allergens, as determined by the skin prick test, was evaluated retrospectively.

RESULTS

The files of a total of 3025 children (63.3 % boys) with bronchial asthma, aged 3 months to 16 years were evaluated. Of the total, 1667 patients with a diagnosis of bronchial asthma and 1358 with bronchial asthma plus allergic rhinitis were under follow-up. Of the 3025 asthmatic patients, 1902 had undergone the skin prick test and 60.3 % of these patients were atopic. The most common allergens were house dust mite [726 patients (63.3 %)], followed by pollens [565 patients (49.3 %)]. The most common allergen within this group was grass pollens [348 patients (30.3 %)].

CONCLUSIONS

Atopy was an important risk factor in our patients and the most common allergens were aeroallegens. The development of sensitization could be delayed by early precautions.

Characterization of immunoglobulin E responses in Balb/c mice against the major allergens of timothy grass (Phleum pratense) pollen

BACKGROUND

Grass pollen, such as that from timothy grass (Phleum pratense), represents a major cause of type I allergy.

OBJECTIVE

To characterize the IgE immune response and to identify the major allergens eliciting an IgE response in a mouse model using pollen extract of P. pratense for sensitization, in order to assess analogies to human hyperreactivity and to gain information on the allergenic potential as determined by the IgE-reactivity kinetics of defined allergens.

METHODS

Balb/c mice were sensitized with pollen extract or with purified natural allergens. Serum IgE levels, the induction of specific IgE antibodies and immediate hypersensitivity were monitored by ELISA, Western blot and a skin test, respectively.

RESULTS

The sensitized mice mounted a strong IgE response and showed IgE-reactivity first against Phl p 5a and 5b, then Phl p 4 and 13 and lastly against Phl p 6. No IgE response was mounted against Phl p 1. However, all purified fractions examined (Phl p 5a, 5b, 6 and 1) induced specific IgE and showed similar kinetics of IgE induction as pollen extract (first Phl p 5a and 5b, then Phl p 6). Skin test experiments demonstrated positive reactivity only in sensitized mice.

CONCLUSION

The IgE reactivity induced by the major allergens in Balb/c mice was very similar to that found in allergic patients, with the exception of Phl p 1. The kinetics of the specific IgE response was comparable using either pollen extract or the purified major allergens, indicating that the intrinsic properties of the allergens are of importance rather than their proportionate amounts in pollen extract. This model should prove to be suitable for investigations regarding the mechanisms of induction and manifestation of timothy grass pollen allergy and for the evaluation of therapeutic strategies.