Identification of major allergens of two species of local snappers: Lutjanus argentimaculatus (merah/ red snapper) and Lutjanus johnii (jenahak/ golden snapper)

Fish has been recognized as a source of potent allergens both in food and occupational allergy. Lutjanus argentimaculatus (red snapper) and Lutjanus johnii (golden snapper) locally known as merah and jenahak, respectively, are among the most commonly consumed fish in Malaysia. The objective of this study is to identify the IgE-binding proteins and major allergens of these species of fishes. Extracts of both fish species were prepared and fractionated by sodium dodecyl polyacrylamide gel electrophoresis (SDS-PAGE). IgE binding patterns were then demonstrated by immunoblotting using sera from patients allergic to the fishes. The raw extracts of both fish produced 26 protein bands. Both species of fishes had similar protein profiles. In cooked extracts, several protein bands in the range of about 40 to 90 kD which were present in the uncooked extracts appeared to be denatured and formed high molecular weight complexes. The immunoblotting of golden snapper and red snapper revealed 16 and 15 various IgE-binding bands, in the range of 151 to 12-11 kD, respectively. A 51 kD protein was identified as a major allergen for both fishes. A 46 kD protein was also demonstrated as a major allergen in golden snapper and a 42 kD protein was also seen as a major allergen in red snapper. A heat-resistant protein of ~12 kD which is equivalent in size with fish parvalbumin was demonstrated only as minor allergen for both fishes.