An air pouch type allergic
inflammation in rats was induced using an insoluble cationic
protein,
methylated bovine serum albumin (MeBSA), as an
antigen. Changes in vascular permeability, local tissue
edema,
histamine contents in the pouch fluid, and number of infiltrated leukocytes and chemotactic activity in the pouch fluid were analyzed during an 8-hour period after injecting the
antigen solution into the air pouch of the immunized and nonimmunized rats. Vascular permeability during the first 30-min interval in the immunized rats was higher than that in the nonimmunized rats, reflecting a higher
histamine level in the pouch fluid. However, both the increase in vascular permeability and
histamine level in the immunized rats in this period were much lower than those induced by a soluble, noncationic
antigen, azobenzenearsonate-conjugated acetyl
bovine serum albumin. In the MeBSA-induced allergic
inflammation model, a second peak of vascular permeability was induced at 2 h, and local tissue
edema formation became apparent at 2 h, reaching a plateau at 4 h. A prominent increase in leukocyte infiltration, especially neutrophils, into the pouch fluid was induced at 4 h in accordance with an increase in chemotactic activity in the pouch fluid. These observations indicate that the acute phase of MeBSA-induced allergic
inflammation is characterized by a weak anaphylactic response and a prominent neutrophil infiltration.