In patients with LTP syndrome food-specific IgE show a predictable hierarchical order.

BACKGROUND: Lipid transfer protein (LTP) is a widely cross-reacting allergen in plant foods.
OBJECTIVE: To assess whether IgE to vegetable foods show predictable trends in LTP allergic patients.
METHODS: Clinical allergy to plant foods other than peach was sought in 15 consecutive peach-allergic adults monosensitized to LTP. IgE specific for peach, apple, hazelnut, walnut, peanut, lentil, maize, soybean, tomato, sesame, mustard melon, kiwi, and celery as well as to mugwort pollen was measured.
RESULTS: Peach-specific IgE levels exceeded IgE to all other study foods. The higher were peach-specific IgE levels, the higher was the probability that other plant-derived foods scored positive. Mean IgE levels specific for all study foods were strongly correlated to peach specific IgE. Food-specific IgE followed a rather precise hierarchy, both in terms of number of positive in-vitro tests and of IgE levels, with apple at the second place after peach, followed by walnut, hazelnut, peanut, lentil, maize, soybean, tomato, kiwi, sesame, mustard, melon, and celery. Such hierarchy was not necessarily paralleled by clinical allergy as lentil, maize, and soybean scored positive in the majority of patients, but induced allergy in 0, 1, and 0 patients, respectively. IgE levels were not necessarily correlated with the severity of clinical allergy. Little or no IgE reactivity to mugwort pollen was found.
CONCLUSIONS: In LTP syndrome, IgE reactivity to foods other than peach is in most cases predictable and follows a regular sequence that probably depends on the degree of homology with Pru p3. The reasons why some foods are tolerated by most patients despite elevated IgE reactivity remains to be elucidated.