Effect of acute-phase proteinase inhibitors on chemotaxis of rat polymorphonuclear leukocytes in vitro.

Abstract
Rat serum obtained at 24 h after subcutaneous injection of carrageenin significantly suppressed chemotaxis of rat polymorphonuclear leukocytes (PMNs) in vitro. .alpha.2 Acute-phase macroglobulin (.alpha.2APM), .alpha.1 proteinase inhibitor (.alpha.1PI) and cysteine-proteinase inhibitors (CPIs) are present at high concentration in the 24-h serum and known as acute-phase reactants in rats. These acute-phase proteinase inhibitors were purified from inflamed rat serum or exudate and their effect on PMN chemotaxis was studied by Boyden''s method in vitro. .alpha.2APM (4 mg/ml) significantly suppressed PMN chemotaxis while .alpha.1M was without effect, though both .alpha.2APM and .alpha.1M had a similar anti-proteinase activity. The results suggest that .alpha.2APM suppressed PMN chemotaxis through the mechanism unrelated to its anti-proteinase activity. On the other hand, .alpha.1PI (1 and 3 mg/ml) slightly but significantly suppressed PMN chemotaxis, whereas CPI-1 and CPI-2 had no inhibitory effect. These results suggest that .alpha.2APM and .alpha.1PI play a role in suppression of PMNs infiltration into the inflammatory site in the late-phase of acute inflammation.