Identification of a specific IgE-binding protein from narrow-leafed lupin (L. Angustifolius) seeds

Since lupin has been introduced as a food ingredient on the market there are more and more reports concerning its allergenic properties. However, only few narrow-leafed lupin proteins have yet been characterized as specific IgE-binding molecules and identified. The aim of the study has been to find and identify the main narrow-leafed lupin globulins that bind to specific IgEs from the sera of lupin-allergic people. Isolated lupin globulins were subjected to immunoblotting with the sera from people who suffered from lupin allergy. Incubation with alpha-methyl-D-galactopyranoside was performed to eliminate possible binding of unspecific human IgEs. The proteins binding specific IgEs from lupin-allergic patients' sera were identified by means of mass spectrometry. Western blot analysis revealed 2 signals corresponding to lupin globulins that bound to specific IgEs from the sera of people allergic to lupin. The globulins were identified as conglutin-gamma and its smaller subunit. The results suggested that individuals that displayed lupin allergy symptoms reacted to conglutin-gamma.

The results of the study can contribute to identification of yet undetected allergens of narrow-leafed lupin. This, in turn, can make lupin-fortified products safer for the consumers.