Induction of active systemic anaphylaxis by oral sensitization with ovalbumin in mast-cell-deficient mice

Mast-cell-deficient W/W-v mice were sensitized by oral administration of 0. 1 and 1.0 mg ovalbumin (OVA) by gavage every day for 9 weeks, and active sy stemic anaphylaxis (ASA) was induced by intraperitoneal injection of OVA. T he production of OVA-specific IgE and IgG1 by oral immunization of the W/W- v mice was high, and the production of IL-4 by splenocytes re-stimulated wi th OVA in vitro was increased. In contrast, production of OVA-specific IgG2 a and IgG2b was low, and production of IFN-gamma by splenocytes after re-st imulation with OVA in vitro was rather decreased. These findings suggest th at Th2-dominant helper T-cell activation had occurred. No increase in serum histamine level was observed following ASA induction. However, the plasma platelet-activating factor (PAF) levels of the mice sensitized with 0.1 and 1.0 mg OVA by gavage increased significantly. The increases in plasma PAF correlated well with the ASA-associated decreases in body temperature, sugg esting that PAF plays an important role in ASA in W/W-v mice. Taken togethe r the above findings indicate that W/W-v mice are a good model not only for studying induction of food allergy but also for examining the role of PAF in food-induced hypersensitivity. (C) 2000 Elsevier Science B.V. All rights reserved.