Lipid-transfer proteins as potential plant panallergens: cross-reactivity among proteins of Artemisia pollen, Castanea nut and Rosaceae fruits, with different IgE-binding capacities

Background Lipid-transfer proteins (LTPs), but not Bet v 1 homologues, have been identified as major allergens of apple and peach in the Rosaceae frui t-allergic population in the Mediterranean area. Many of these patients sho w cosensitization to mugwort pollen. LTPs have an ubiquitous distribution i n tissues of many plant species, and have been proposed as a novel type of plant panallergens. Objective We sought to isolate LTPs from Artemisia pollen and from a plant food not belonging to the Rosaceae family, such as chestnut nut, and to com pare their amino acid sequences and IgE-binding capacities with those of ap ple and peach LTPs. Methods Allergens (LTPs) were isolated by different chromatographic methods (gel-filtration, ion exchange and/or reverse-phase HPLC), and characterize d by N-terminal amino acid sequencing and MALDI analysis. Specific IgE-quan tification and immunodetection, as well as immunoblot and ELISA inhibition assays, were carried out using sera from patients allergic to both apple an d peach. Results Purified LTPs from Artemisia pollen and from chestnut seed showed m olecular masses about 9 700d, and 43-50% sequence identity with the equival ent allergens of apple and peach in the first 30 N-terminal residues, which comprise about one third of the total amino acid sequence. A similar degre e of sequence identity (50%) was found between the Artemisia and chestnut p roteins. Both isolated LTPs bound specific IgE of sera from Rosaceae fruits allergic patients. However, substantially lower values of specific IgE-bin ding and maximum ELISA inhibition percentages were obtained for Artemisia a nd chestnut LTPs when compared to those from apple and peach. Conclusion LTPs from Artemisia pollen and chestnut crossreact with allergen s (LTPs) of Rosaceae fruits, but significant differences in specific IgE-bi nding capacities were observed among members of the plant LTP family. Thus, further studies are needed to evaluate the clinical significance of the ob served cross-reactivities of plant LTPs.