Acute inflammation following intraperitoneal injection of antigen into actively sensitised rats.

Rats actively sensitised to bovine serum albumin (BSA) in Freund's complete adjuvant were challenged by intraperitoneal injection of BSA. By washing out the peritoneal cavities at different times it was possible to divide the changes that occurred into two phases. The first was characterised by the release of histamine and slow reacting substance of anaphylaxis (SRS-A) with an associated extravasation of plasma proteins. The second phase was characterised by an increase in neutrophilic polymorphonuclear cells in the peritoneal cavity. Extracellular enzyme activites were also investigated. The kinetics of these events were studied and are discussed in terms of the possible mechanisms involved.