Recurrent anaphylaxis due to lupin flour: primary sensitization through inhalation.

Allergic reactions to lupin have increased in parallel with the growing use of lupin flour by food manufacturers. We studied a patient with recurrent anaphylaxis to manufactured foods and a history of rhinitis-asthma related to lupin inhalation and legume tolerance. Skin prick tests with airborne and food allergens, specific immunoglobulin (Ig) E determinations, and an inhalation exposure test to ground lupin were carried out. Lupin allergens and cross-reactivity with other legumes were also studied using sodium dodecyl sulfate polyacrylamide gel electrophoresis and immunoblotting/immunoblotting inhibition. The skin tests and specific IgE were positive for lupin and vetchling and negative for other legumes. The presence of lupin flour in the implicated foods was confirmed. Immunoblotting showed multiple IgE-binding bands (10-40 kDa) for lupin and vetchling but not for peanut, pea, or soy extracts. Immunoblotting inhibition demonstrated intense lupin-vetchling cross-reactivity. We present a case of recurrent anaphylaxis due to lupin flour as a hidden food allergen with primary sensitization due to exposure to ground lupin via inhalation. We found cross-reactivity between lupin and vetchling but not other legumes.