Regulation of the Immune Response to Allergens by Immunosuppressive Allergenic Fragments

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.