Regulation of the immune response to allergens by immunosuppressive allergenic fragments. 1. Peptic fragments of honey bee venom phospholipase A2.

Nine patients with anaphylactic sensitivity to honey bee venom (HBV) were treated with P-1, a pepsin derived fragment of HBV phospholipase A2 (PLA2). P-1 caused only rare reactions with doses of 100 micrograms/injection. Treatment resulted in a substantial decrease in specific anti-PLA2 IgE and IgG antibodies as well as a decline in skin test sensitivity to PLA2. Another group of HBV-sensitive patients was treated with unaltered PLA2. Doses greater than 20 micrograms/injection were not tolerated. PLA2 injections caused an increase in anti-PLA2 IgG and IgE antibodies as well as increase in skin test sensitivity. This study demonstrates that a nonimmunogenic fragment derived from an allergen can downregulate immune responses and thus offer a new modality for therapy of allergic diseases.