Swiss chard hypersensitivity: clinical and immunologic study.

Allergy to vegetables and fruits seems to be more prevalent in atopics, especially in birch pollen-sensitized individuals. We report a case of a grass pollen-sensitized woman, in whom the inhalation of vapor from boiling Swiss chard precipitated rhinoconjunctivitis and asthma. Type I hypersensitivity to Swiss chard was demonstrated by means of immediate skin test reactivity, specific IgE determination by RAST, basophil degranulation, histamine release test, and an immediate bronchial provocation test response to Swiss chard extract. The controls did not react to any of these tests. RAST inhibition assays suggest the presence of some cross-reactivity among Swiss chard and grass pollen antigens, as well as cross-reactivity between vegetables and weed pollens of the chenopod family.