Comparison of IgE reactivity of recombinant and natural pen a 1 by RAST and mediator release

Abstract

Rationale Pen a 1 is the major shrimp allergen of Penaceus aztecus and has been identified as the muscle protein tropomyosin. It is responsible for the majority of IgE-mediated hypersensitivity to shrimp. Since recombinant proteins may be useful in diagnosis and treatment of food allergic individuals, recombinant Pen a 1 (rPen a 1) was cloned and expressed in E. coli. This study was performed to compare the immunological activity of rPen a 1 and natural Pen a 1 (nPen a 1) by RAST and mediator release. Methods Sera from six shrimp-allergic individuals with positive skin tests to shrimp extract were tested. RAST was performed using discs coated with whole shrimp extract, nPen a 1 (purified by preparative SDS-PAGE), and rPen a 1 at different concentrations (10.0 - 0.01 μg per disc). Peanut-coated discs were used as controls. Mediator release was performed by sensitizing humanized rat basophilic leukemia cells with human IgE from shrimp-allergic individuals. Results All six of the shrimp-allergic sera had RAST reactivity at all concentrations to both nPen a 1 and rPen a 1. Non-allergic control sera did not show reactivity. Linear regression analysis demonstrated identical IgE antibody binding capacity of rPen a 1 and nPen a 1. This was confirmed by the mediator release assay. Conclusion The use of rPen a 1 may have a role in determining shrimp-allergic individuals. Since this study is small, further serological testing should be conducted to confirm these results and skin testing with rPen a 1 should be performed.