Inflammatory Role of Two Venom Components of Yellow Jackets (Vespula vulgaris): A Mast Cell Degranulating Peptide Mastoparan and Phospholipase A1

Background: Venom sac extract of yellow jackets Vespula vulgaris was toxic in mice when injected intraperitoneally but not toxic when injected subcutaneously. Necropsy showed the toxicity to be an inflammatory response. Methods: Venom peptide and protein fractions were tested to identify the inflammatory components. The active components were tested to establish whether they might function as adjuvant for venom protein-specific antibody response. Results: Venom toxicity required the synergistic action of two venom components, a mast cell degranulating peptide mastoparan and phospholipase A1. Both components stimulated prostaglandin E 2 release from murine peritoneal cells and macrophages. Mastoparan showed a weak activity to enhance IgE and IgG1 responses to a yellow jacket venom protein Ves v 5 in BALB/c mice. It was not possible to assess the adjuvant activity of phospholipase A1 because of its suppression of Ves v 5-specific response. Melittin, a mast cell degranulating peptide from bee venom, was inactive as an adjuvant for Ves v 5-specific response. Conclusion: Yellow jacket venom contains two inflammatory components, mastoparan and phospholipase A1. Our findings suggest that mastoparan can function as a weak adjuvant for TH2 cell-associated antibody response.