The involvement of thaumatin-like proteins in plant food cross-reactivity: a multicenter study using a specific protein microarray

Abstract

Cross-reactivity of plant foods is an important phenomenon in allergy, with geographical variations with respect to the number and prevalence of the allergens involved in this process, whose complexity requires detailed studies. We have addressed the role of thaumatin-like proteins (TLPs) in cross-reactivity between fruit and pollen allergies. A representative panel of 16 purified TLPs was printed onto an allergen microarray. The proteins selected belonged to the sources most frequently associated with peach allergy in representative regions of Spain. Sera from two groups of well characterized patients, one with allergy to Rosaceae fruit (FAG) and another against pollens but tolerant to food-plant allergens (PAG), were obtained from seven geographical areas with different environmental pollen profiles. Cross-reactivity between members of this family was demonstrated by inhibition assays. Only 6 out of 16 purified TLPs showed noticeable allergenic activity in the studied populations. Pru p 2.0201, the peach TLP (41%), chestnut TLP (24%) and plane pollen TLP (22%) proved to be allergens of probable relevance to fruit allergy, being mainly associated with pollen sensitization, and strongly linked to specific geographical areas such as Barcelona, Bilbao, the Canary Islands and Madrid. The patients exhibited >50% positive response to Pru p 2.0201 and to chestnut TLP in these specific areas. Therefore, their recognition patterns were associated with the geographical area, suggesting a role for pollen in the sensitization of these allergens. Finally, the co-sensitizations of patients considering pairs of TLP allergens were analyzed by using the co-sensitization graph associated with an allergen microarray immunoassay. Our data indicate that TLPs are significant allergens in plant food allergy and should be considered when diagnosing and treating pollen-food allergy.

Figure 1. Frequency of sensitization obtained by the TLP microarray using sera from both fruit-allergic (FAG) patients, and non-food pollen allergic (PAG) subjects.

Odds ratios are presented in parentheses (95% CI; p<0.001).

Figure 2. IgE binding inhibition of the TLP microarray, when serum pool (n = 21; three per area) or individual sera were preincubated for 3 h at room temperature with increasing amounts of Pru p 2.0201, and chestnut and plane -pollen TLPs.

Figure 3. Frequency of sensitization in the different geographical areas using the homemade microarray and sera from fruit-allergic (FAG) patients, and non-food pollen-allergic (PAG) subjects.

Only TLPs with more than 10% positive response were represented: Pru p 2.0201, Pru p 2.0101, chestnut, plane, lettuce and cabbage TLPs.

Figure 4. Co-sensitization graph of TLP allergens.

Each node represents one allergen (TLP as white ellipses, non-TLP allergens as blue square nodes, and LTP-allergen Pru p 3 as a green diamond) and the links represent co-sensitization of one or more sera for the linked allergens. The weight of each link, ranging between 0 and 1, measures the degree of co-sensitization. For the sake of clarity, only the 25 links of weight greater than 0.50 out of the total 253 existing links were plotted.