Mast cell protease release and mucosal ultrastructure during intestinal anaphylaxis in the rat.

Intestinal anaphylaxis is associated with disturbances in gut function that are antigen-specific and dependent on mast cell degranulation. Using an animal model of intestinal anaphylaxis, we have correlated alterations in water and electrolyte transport, associated with intraluminal challenge, with specific intestinal mucosal mast cell degranulation by following systemic as well as local release of rat mast cell protease II. This protease is specific for intestinal mucosal mast cells and is known to selectively attack type IV collagen, which is found in basement membranes. Intraluminal antigen challenge in sensitized animals dramatically increased serum and intraluminal levels of rat mast cell protease II. Serum levels continued to rise throughout the duration of antigen challenge. Although light microscopy of challenged intestine demonstrated little distortion of mucosal architecture, ultrastructural examination revealed significant disruption to the basement membrane and underlying collagenous matrix of the intestinal mucosa. Our findings indicate that during mucosal immunoglobulin E-mediated reactions, rat mast cell protease II is released and is associated with ultrastructural changes in the intestinal mucosa. The systemic appearance of this specific protease provides a serum marker of intestinal anaphylaxis.