Lipid transfer protein sensitization: reactivity profiles and clinical risk assessment in an Italian cohort.

BACKGROUND: Nonspecific lipid transfer proteins (nsLTPs) represent a major cause of systemic food allergic reactions in the Mediterranean area. This study investigate hierarchical patterns and cluster relationships of IgE sensitization to different nsLTPs, and the relationship to clinical allergy in a large Italian cohort. METHODS: A total of 568 nsLTP-positive subjects after IgE ImmunoCAP-ISAC microarray analysis with Ara h 9, Art v 3, Cor a 8, Jug r 3, Pla a 3, Pru p 3 and Tri a 14 allergens were studied. IgE inhibition experiments were carried out with mugwort and plane tree pollen extracts. RESULTS: Eighty-two per cent of nsLTP-positive participants (94% if <6 years old) were Pru p 3(pos) , and 71% were Jug r 3(pos) . Participants who reacted to >5 nsLTPs reported a higher incidence of food-induced systemic reactions. Only Art v 3 and Pla a 3 (mugwort and plane tree nsLTPs, respectively) were associated with respiratory symptoms, and a correlation was observed between sensitization to pollen and plant food nsLTPs, particularly between Pla a 3 and tree nut/peanut nsLTPs. Co-sensitization to Par j 2 and PR-10 or profilin pan-allergens was associated with a lower prior prevalence of severe food-induced reactions. In inhibition assays, plane and mugwort pollen extracts inhibited 50-100% of IgE binding to food nsLTPs in microarrays. CONCLUSIONS: Testing IgE reactivity to a panel of nsLTP allergens unveils important associations between nsLTP sensitization profiles and clinical presentation and allows the identification of novel cluster patterns indicating likely cross-reactivities and highlighting potential allergens for nsLTP immunotherapy.

Evaluation by double-blind placebo-controlled oral challenge of the clinical relevance of IgE antibodies against plant glycans.

BACKGROUND: The clinical relevance of immunoglobulin E (IgE) to plant glycans is a longstanding debate. We sought to evaluate their clinical reactivity using the human glycoprotein lactoferrin expressed in rice. METHODS: Allergic patients with IgE antibodies against plant glycans were analyzed for the presence of IgE against rice-produced lactoferrin. The potency of IgE to induce mediator release was assessed by basophil histamine release and skin prick tests (SPTs). Clinical relevance was evaluated by double-blind placebo-controlled oral challenge (DBPCOC). RESULTS: Twenty-four of 29 sera (82.7%) with IgE antibodies against plant glycans demonstrated IgE binding to transgenic lactoferrin. In three of five cases transgenic lactoferrin induced histamine release. Compared to a control major grass pollen allergen lactoferrin concentrations needed for biological activity of IgE were 5-6 orders of magnitude higher. Skin prick test and DBPCOC were negative in five patients with potential clinical reactivity that volunteered to undergo these in vivo challenges. CONCLUSIONS: Poor or no biological activity and lack of clinical relevance of IgE-binding plant glycans (five out of five) was demonstrated using human lactoferrin expressed in rice as a model.