Summary: | Bee stings are a common health problem throughout the world and can sometimes result in fatal anaphylactic reactions. We have studied Asian bee (Apis cerana indica, Apis cerana nigrocincta and Apis dorsata) venoms and have discovered a novel protein with a molecular size of 50 kDa (p50), as shown by sodium dodecyl sulfate–polyacrylamide gel electrophoresis, which has not been reported in the venom of the Western honey-bee, Apis mellifera (AM). The p50 protein showed a unique affinity to human α1-microglobulin (α1-m). As a result, p50 was purified using an affinity column with α1-m. The p50 protein was further purified by an affinity column with a monoclonal antibody raised against p50 in mice. The p50 protein induced an inflammatory reaction following injection into mouse ear; that is, degranulation of mast cells, edema, hyperemia and hyperpermeation of the local capillaries were observed. The reaction was very similar to that seen when phospholipase A2 of AM, a representative bee venom, was administered by injection. The inflammatory reaction induced by p50 was completely inhibited by mixing p50 with α1-m prior to injection. These results indicate that p50 is a unique venom component of the Asian bee that induces the inflammatory reaction and that human α1-m may be involved as a protective mechanism against bee stings of at least some Asian bee species.
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