Pattern of immunoreactivity to fish proteins in allergic patients

Seafood has an important nutritional role in human diet. A certain number of allergic reactions has been observed, as a consequence of the increased consumption of certain fishes. The incidence of allergy to fish in the world ranges between 0.2 and 2.29% in the general population (1). The main clinical manifestations are vomiting and diarrhea up to anaphylactic shock. The major fish allergen is parvalbumin, a protein having molecular weight close to 11-12 kDa; its biological role is the regulation of calcium switching in muscular skeletal cells. Parvalmbumin represents the most important clinical cross-reactive fish protein in allergic patients. Other fish allergens have been identified, such as collagen, enolase, aldolase and vitellogenin. The aims of this research were the evaluation of 1) the electrophoretic protein patterns in different fishes; 2) the pattern of IgE-mediated immunoreactivity by using the serum from allergic patients. To reach these objectives, proteins from the most usually consumed fish species were separated by SDS-PAGE under reducing conditions, and then proteins were transferred to a PVDF membrane, by Western blotting, and incubated with sera from allergic patients. Raw and cooked fishes were compared and they presented some significant differences in the electrophoretic profile. In all the samples, a band with 12-14 kDa, corresponding to parvalbumin, was present. The sera from allergic subjects showed different immunoreactivity versus raw and cooked samples. Moreover, parvalbumin was not always identified by IgEs from allergic patients while other allergens were more immunoreactivity allowing some conclusion on the role of each allergen in the observed clinical pattern.