Allergy to insect stings. II. Phospholipase A: the major allergen in honeybee venom.

In order to determine the proteins of major allergenic importance in honeybee venom (Apis mellifera) it was chromatographed on G-50 Sephadex. The four major protein peaks eluted were identified as hyaluronidase, phospholipase, melittin, and apamin. Testing these preparations on the leukocytes of 6 honeybee-sensitive patients, with the in vitro method of histamine release, revealed that all individuals were most sensitive to phospholipase A. IgE antibodies against phospholipase A (RAST) were found in the sera of honeybee-sensitive patients and IgG antibodies to this venom component were found in the sera from beekeepers and venom-treated patients. Melittin appeared to be allergenic in several patients, but the results were variable and were possibly due to contamination with phospholipase. All patients were insensitive to the hyaluronidase and apamin preparations. We conclude that phospholipase A is the major allergen of honeybee venom and, since this protein is readily available, it should be useful for diagnostic and therapeutic studies as well as for the standardization of materials used in the management of honeybee-sensitive patients.