SENSITIZATION TO SUNFLOWER POLLEN - ONLY AN OCCUPATIONAL ALLERGY

Sunflower (Helianthus annuus) pollen sensitization has been reported a s an occupational allergy. In this report, the sensitization of the ge neral population living in sunflower-growing areas to Helianthus polle n was studied. Both RAST results in 32 adults with summer symptoms pre viously diagnosed as allergic to Artemisia pollen, and cross-reactivit y studies between H. annuus and other Compositae suggested that H. ann uus pollen was the main allergen involved in the hypersensitivity reac tion of those patients. Good correlation was found between RAST and SP T to Helianthus and between RAST and conjunctival provocation test to Helianthus. Bronchial challenge tests performed on 8 of the 32 patient s confirmed the clinical implication of Helianthus pollen in suspected subjects. Five workers, handling sunflower pollen, who suffered from related symptoms were subjected to the same study, showing lesser whea l areas and lesser specific IgE levels than a non-worker group. Thirte en patients with RAST values greater than or equal to class 2 showed 2 IgE-binding fractions at 34.0 and 42.8 kD in 65% of sera and 3 IgE-bi nding fractions at pI 4.9, 9.6 and 10.2 in 54% of sera. By means of mi cropreparative high-resolution chromatography, it was possible to puri fy a 34-kD major allergen. Analysis performed by RAST inhibition with sera from atopic patients and ELISA inhibition with experimental anti- Helianthus rabbit sera demonstrated a cross-reactivity between Heliant hus and other Compositae, but low affinity of specific anti-Helianthus antibodies for heterologous antigens. Taking into account the above-m entioned data, and the high prevalence of Helianthus pollen in the atm osphere during harvesting (in spite of its entomophilous character), H elianthus pollen should be considered as an allergenic source to be in vestigated in the general population living in sunflower-growing regio ns suffering from seasonal summer allergy.