Inflammation is accompanied by leukocyte activation (LA). We describe a simple ex vivo technique for studying LA that might help to find new LA inhibitors for the treatment of pathologic events related to LA. Arterial and venous blood samples obtained from six permanently catheterized beagle dogs -60, 0, +15 min and +23 h after i.v. challenge with C 48/80, and also blood samples from six normal beagles, were minimally diluted 1:2.5 with buffer. Total leukocyte counts (LC), and luminol amplified CL, induced by opsonized zymosan (C3-Z), were estimated. Blood samples from dogs elicited CL responses of almost 1/10 the magnitude of erythrocyte-free human leukocytes, whereas blood samples from rats reacted three orders of magnitude less. Obviously quenching of CL by accompanying erythrocytes in blood samples from dogs is not important, for CL correlated almost linearly with the CL in differently diluted samples. In arterial, but not in venous samples from catheterized dogs, absolute CL and LC, both were significantly depressed (p less than or equal to 0.05) 15 min after C 48/80 challenge. CL/10(6) leukocytes was augmented twofold. All leukocyte deviations returned to pre-values 23 h post-challenge.

A thrombin-like proteinase (THROLP) was detected colorimetrically as the main proteolytic activity (PROA) in the lavage fluid some minutes after antigen challenge of rats for passive peritoneal anaphylaxis (PPA) reaction. THROLP is equivalent to histamine (H) as parameter for the early phase of PPA: both increased significantly after 6 min, but decreased to prechallenge levels 20 min after challenge. H was released from serosal mast cells, in contrast THROLP originates predominantly from plasma leakage and activation of the clotting reaction in PPA. These findings underline the importance of PROA in the sequence of allergic reactions.