The major shrimp allergen has been isolated and identified as a tropomyocin based on a comparison of amino acid sequences of different peptides generated by proteolysis of the parent molecule. Dot blot and competitive ELISA inhibition using sera of shrimp sensitive patients revealed that antigenic as well as allergenic activities were associated with two peptides. These peptides have been sequenced. These two peptides are similar between cross-reacting Crustaceae, but vary between tropomyosin from phylogenetically distinct species. Anti-idiotypic antibodies (Ab-2) are the mirror images of idiotypic antibodies (Ab-1q). Murine Ab-2 raised by immunizing mice with AB-1 specific for Parthenium hysterophorus functioned as surrogate allergens in in vitro diagnostic tests. Surrogate allergens may be of value in allergen standardization and for in vitro diagnosis particularly when it is difficult to obtain and purify specific allergens in large quantities. MSG is a GRAS substance used to enhance the flavor of foods. Double- blind placebo controlled challenges of both normal and asthmatic subjects with MSG did not provoke asthma. MSG administered before methacholine challenge did not alter bronchial reactivity to methacholine.
