Melittin: an allergen of honeybee venom.

The presence of serum IgE antibodies to melittin was tested by the radioallergosorbent test (RAST). Melittin, the principal protein of honeybee venom, was isolated by gel filtration on Sephadex G-75 and covalently bound to cyanogen bromide-activated microcrystalline cellulose. The melittin preparation was homogenous by immunoelectrophoresis with the use of rabbit antiserum to whole honeybee venom and by polyacrylamide electrophoresis in gels containing 1% sodium dodecyl sulfate. Elevated serum IgE antibodies to melittin (three times greater than binding by normal sera) were found in 7 of 24 honeybee venom-sensitive persons and in 5 of 20 nonsensitive beekeepers. In one venom-sensitive patient a particularly high titer of IgE antibody was found. The reaction between solid-phase melittin and IgE antibody could be inhibited by fluid-phase melittin but not by phospholipase A (PLA). Similarly, the reaction of IgE antibody with solid-phase PLA was inhibited by PLA but not by melittin. In passive transfer skin tests with the sensitive patient's serum, positive wheal-and-flare reactions were obtained in 3 nonallergic recipients following melittin challenge; appropriate controls were negative. These results indicate that melittin is an allergen in some honeybee venom-sensitive patients and in an occasional patient melittin may be a major allergen.