[Asthma related to inhalation of Plantago ovata]

Psyllium is the seed of the plant Plantago ovata, which is widely used in nonprescription laxatives. It has been reported that psyllium powder may act as an inhalant allergen, especially in the workplace. A patient with asthma due to inhalation of P. ovata seed powder is described, being highlighted the allergenic potential of this substance frequently used as a laxative. We report a 31 year-old atopic woman, who handled and prepared at home, twice daily, a laxative containing P. ovata seeds (Plantaben) prescribed to her paralytic mother.

Skin prick test to psyllium powder extract was positive. Specific IgE antibodies to psyllium were positive as determined by ELISA. Methacholine inhalation test revealed mild bronchial hyperresponsiveness (PC20 = 1.5 mg/ml). Specific bronchial challenge to psyllium powder elicited an isolated early asthmatic response. The allergens in psyllium were investigated by SDS-PAGE and immunoblotting, being identified several allergenic components with an apparent molecular weight of 66, 60, 36-20 and 14 kDa. No cross-reactivity was found between P. ovata seed and P. lanceolata pollen, as determined by ELISA-inhibition.

Psyllium may act as a potent inhalant allergen capable of eliciting asthma symptoms, not only in an occupational context, but also in a domestic environment, affecting consumers of this laxative or relatives who handle it.