Lipid transfer proteins and 2S albumins as allergens.

Plant lipid transfer proteins, a widespread family of proteins, have been recently identified as important food allergens. Their common structural features, such as eight conserved cysteines forming disulfide bridges, basic isoelectric point and high similarity in amino acid sequence, are the basis of allergic clinical cross-reactivity. This has been demonstrated for the LTP allergens of the Prunoideae subfamily, whose similarity is about 95% as demonstrated for the purified allergens of peach, apricot, plum and apple. A relevant aspect is the existence of sequence homology of LTPs of botanically unrelated foods, as demonstrated for LTPs of maize and peach. A class of food allergens of well recognized clinical importance is that of seed storage 2S albumins. They have been identified in the most diffused edible seeds and nuts, such as mustard, sesame, Brazil nut, walnut and peanut. In particular, a strong correlation between IgE-binding to these proteins and food-induced anaphylaxis has been demonstrated for Brazil nut and sesame seeds.