Identification of allergens in the venom of the common striped scorpion.

Background: The common striped scorpion, Centruroides vittatus, is endemic to the southwestern United States and causes thousands of human stings annually. Immediate hypersensitivity reactions to C. vittatus venom have been reported.

Objectives: To identify specific IgE in 11 patients with immediate hypersensitivity to C. vittatus and to characterize the allergens present in the venom.

Methods: Skin testing to dialyzed, filtered venom was performed in 5 patients. Immunoglobulin E immunoblots to whole milked venom was accomplished with serum samples from 8 patients. Enzymatic properties of whole venom were also determined.

Results: C. vittatus venom was found to contain 150 microg/microL of protein. Four of 5 patients tested had positive skin test reactions to the purified venom extract, with no late reactions. In all 8 patients, sodium dodecyl sulfate-polyacrylamide gel electrophoresis demonstrated multiple proteins, 9 of which were identified as allergens on IgE immunoblots, ranging in size from 30 to 170 kD. Enzymatic activity was found to include phospholipase A, alkaline phosphatase, esterase, esterase lipase, and acid phosphatase.

Conclusions: C. vittatus envenomation may result in immediate hypersensitivity reactions in susceptible individuals. Venom specific IgE can be identified by using skin tests and IgE immunoblots. The allergens identified in these patients had molecular weights distinct from those of known scorpion neurotoxins. A safe and effective skin testing extract can be prepared from dialyzed pure venom and may lead to the widespread ability to diagnose C. vittatus venom allergy.