CHARACTERISTICS OF HYPERSENSITIVITY REACTIONS AND IDENTIFICATION OF AUNIQUE 49 KD IGE-BINDING PROTEIN (HAL-M-1) IN ABALONE (HALIOTIS-MIDAE)

Background: There is a paucity of published data on the clinical prese ntation and the nature of the allergens involved in hypersensitivity t o mollusks. This study reports the clinical and immunologic findings i n 38 patients with reported immediate and delayed adverse reactions to abalone (Haliotis midae, Class Gastropoda). Methods: Patients were re cruited as part of a South African seafood allergy survey, Allergic sy mptoms were assessed by a self-administered questionnaire, A total of 38 patients with abalone sensitivity were recruited, Specific IgE resp onses to abalone and other mollusks were studied by using RAST and inh ibition ELISAs, Skin prick tests and lymphocyte proliferation assays m ere also performed on several of the subjects, Allergenic components o f Haliotis midae were identified with Western blotting. Results: Twent y five of the 38 patients in the study were first seen with immediate symptoms, and 13 had delayed reactions. Seventeen of the sera tested w ere RAST positive. Skin prick tests responses with abalone extract mer e positive in all subjects with positive RAST responses (n = 8) and in 6 of 13 subjects with negative RAST responses. Five of the subjects w ith positive RAST responses had positive results on Western blotting a nd demonstrated binding to two major allergens with molecular weights of 38 and 49 kd. The 49 kd IgE-binding protein has been designated as Hal-m-1. Conclusions: Abalone allergens are heat-stable proteins,vith molecular weights of 38 and 49 kd, later designated as Hal-m-1 accordi ng to International Union of Immunological Societies allergen nomencla ture regulation. Our studies indicate a clear clinical and immunologic heterogeneity in patients reactive to abalone.