An observational study on outgrowing food allergy during non-birch pollen-specific, subcutaneous immunotherapy.

BACKGROUND: Birch pollen-specific immunotherapy (SIT) decreases allergy to foods containing birch pollen-homologous allergens. Cross-reactivity was also observed between plane tree pollen and some vegetable foods. OBJECTIVE: The aim of this study was to evaluate the outgrowing of food allergy by patients suffering from vegetable food allergy associated with plane tree pollinosis (rhinoconjunctivitis and/or asthma) during plane tree pollen SIT. METHODS: An observational and prospective study was conducted in 16 adult patients suffering from vegetable food allergy (hazelnut, walnut, lettuce, peach and cherry) and from plane tree pollinosis receiving plane tree pollen SIT for 1 year. Open oral challenges with the implicated food were performed before and after SIT. Blood samples were drawn for measurement of pollen- and food-specific IgE and IgG4 before and after treatment. RESULTS: Plane tree SIT resulted in a significant decrease in food allergy, since the mean food quantity provoking objective symptoms increased from 2.19 to 13.74 g (p < 0.05), and 6 of the 11 patients tolerated the highest level (25 g) of the challenged food after plane tree SIT. Laboratory data also showed a decrease in IgE levels and an increase in IgG4 levels after immunotherapy. CONCLUSION: SIT with plane tree pollen has a positive impact on food allergy in plane tree pollen-allergic subjects.

IgE reactivity to profilin in Platanus acerifolia pollen-sensitized subjects with plant-derived food allergy.

BACKGROUND: The presence of profilin-specific IgE antibodies is a cause of cross-reactivity between botanically-unrelated allergen sources. Recently, the association between Platanus acerifolia pollinosis and plant-derived food allergy has been described. The aim of this study was to ascertain whether the P. acerifolia profilin is involved in such cross-reactivity. METHODS: Twenty-three patients suffering from Platanus acerifolia pollinosis and plant-derived food allergy were evaluated in an allergy department. Specific IgE levels to P. acerifolia pollen, P. acerifolia profilin and food extracts were measured. Molecular masses of IgE-binding proteins were calculated by Western blotting and cross-reactivity studies among P. acerifolia profilin and different food extracts were evaluated by Enzyme AllergoSorbent Test (EAST)-inhibition assays. Also, EAST-inhibition assays with the two known P. acerifolia allergens, Pla a 1 and Pla a 2, were performed. RESULTS: Surprisingly, a high IgE-binding prevalence (90%) of P. acerifolia profilin was found. EAST-inhibition showed high inhibition values when Platanus acerifolia pollen extract was used as free phase and plant-derived food extracts as solid phase, whereas the other way round showed low inhibition values. IgE reactivity to profilin was studied using a pool of patient sera, by EAST-inhibition assays with hazelnut, apple peel, peanut, chickpea and peanut extracts as solid phase and no inhibition was obtained when P. acerifolia profilin was used as inhibitor phase. The same results were obtained when purified Pla a 1 and Pla a 2 were also used as inhibitor phase. CONCLUSIONS: The clinical association observed between Platanus acerifolia pollen and plant-derived food could be explained by the in vitro IgE cross-reactivity detected by EAST-inhibition. However, it appears that neither P. acerifolia profilin nor the two major allergens described (Pla a 1 and Pla a 2) can explain such a strong cross-reactivity.

Lettuce anaphylaxis: identification of a lipid transfer protein as the major allergen.

BACKGROUND: Allergy to plant-derived foods is associated with birch pollinosis in central and northern Europe. Symptoms elicited are usually limited to the oropharyngeal system. By contrast, in the Mediterranean area, allergy to the same foods manifests more frequently with systemic reactions caused by nonspecific lipid transfer proteins (nsLTP), independently of an associated pollinosis. OBJECTIVE: We sought to investigate the pattern of immunoglobulin E (IgE) binding protein bands implicated in lettuce allergy, in particular the presence of an nsLTP. METHODS: Consecutive lettuce allergic patients were selected. Determination of serum-specific IgE, immunoblot, and inhibition experiments were performed in order to study the pattern of IgE binding proteins and the potential cross-reactivity to pollens. Inhibition studies with recombinant allergens were conducted to identify the lettuce allergens. The major allergen was subjected to N-terminal amino acid sequencing. RESULTS: Fourteen patients were diagnosed as being allergic to lettuce. All were sensitized to Platanus pollen. Ten of them showed specific IgE to a lettuce protein of 9-kDa. The IgE binding to this protein was completely inhibited by the cherry-LTP and peach extract. The N-terminal sequence of the 9-kDa protein showed a high degree of amino acid sequence identity to other nsLTPs. A clear partial cross-reactivity was observed between lettuce-LTP and Platanus-pollen extract. CONCLUSIONS: An LTP has been demonstrated to be a major allergen in patients suffering from lettuce allergy.

Platanus acerifolia pollinosis and food allergy.

BACKGROUND: In Mediterranean areas, oral allergy syndrome (OAS) occurs independently of an associated birch pollinosis; moreover, on occasions it presents with no other associated pollinosis. The aim of this study was to assess the possible association of OAS with Platanus acerifolia pollinosis. METHODS: We evaluated consecutive patients seen for pollinosis in an allergy department. Seven hundred and twenty patients were selected on the basis of seasonal or perennial rhinitis, or asthma, or both. Respiratory and food allergies were studied in all patients. Clinical history was recorded and examinations and skin prick tests were performed with a battery of available common inhalant allergens and plant-derived food allergens. Specific IgE levels to P. acerifolia pollen extract and food allergens tested were measured. Molecular masses of the IgE-binding proteins and cross-reactivity among the P. acerifolia pollen and different food extracts were also determined. RESULTS: Of the 720 patients evaluated, 61 (8.48%) were sensitized to P. acerifolia pollen. Food allergy was observed in 32 (52.45%) of the 61 patients sensitized to P. acerifolia pollen. Food allergens most frequently implicated were hazelnuts, peach, apple, peanuts, maize, chickpea and lettuce. Enzyme allergosorbent (EAST)-inhibition showed high inhibition values when P. acerifolia pollen extract was used as free phase. On the contrary low inhibition was observed when plant-derived food allergens were used as free phase and P. acerifolia pollen extract as solid phase. CONCLUSIONS: Cross-reactivity was observed among P. acerifolia pollen and plant-derived foods. OAS in these patients may have been caused by primary respiratory sensitization.