The major heat stable allergen of shrimp

Serum from a patient who had experienced several episodes of anaphylaxis after eating shrimp was used to monitor the isolation of a major allergen from shrimp, which was then tested with sera from 10 other shrimp-reactive patients. The allergen was isolated from a fresh extract of boiled shrimp by gel filtration and from raw shrimp by gel filtration and agarose electrophoresis. The purity of the allergen was established by crossed immunoelectrophoresis against rabbit and guinea pig antisera; it gave only a single peak in each case. The native allergen was excluded on Sephadex G-200 but showed a single band at 38000d in SDS-PAGE with or without reduction. The isoelectric point was about 4.5. The allergen contained about 4% carbohydrate and only 7 Tyr and 9 Phe out of 341 amino acid residues. Using the RAST with 11 allergic sera, the allergen gave a correlation coefficient of 0.98 with whole cooked shrimp extract and of 0.66 with raw shrimp extract. The allergen was a potent inhibitor of RAST to both cooked and raw shrimp. A second, weaker allergen of 21000d chain size was isolated from raw shrimp in highly purified form.