Partial characterization and identification of chemokinetic factors in serum

The chemokinetic effect of serum, defined as the stimulation of the rate of polymorphonuclear neutrophil (PMN) migration in the presence of serum has been investigated for the purpose of identifying the major factors in serum contributing to this effect. The chemokinetic activity has been measured in fresh and heated (56 degrees C) serum and in fractions of serum separated by gel filtration. Gel filtration showed the existence of at least three heat-stable chemokinetic factors with approximate molecular weight of 800,000, 150,000, and 70,000. By immunoprecipitation and immunoadsorption the 800,000 mol. wt factor was identified as alpha 2-macroglobulin and the 70,000 mol wt. factor as alpha 1-antitrypsin and orosomucoid. Heat-labile chemokinetic activity was found in fractions representing mol. wts around 200,000 and 50,000. Immunoprecipitation and immunoadsorption indicated that these heat-labile chemokinetic factors were C3-associated. This investigation suggests a new functional role for the acute-phase reactants alpha 2-macroglobulin, alpha 1-antitrypsin, orosomucoid, and C3 in the modulation of PMN migration and also suggests that the chemokinetic activities of these substances are regulated by specific antagonists at various levels.