α₂M-Proteinase Complexes are Taken up by Macrophages During Joint Inflammation

Abstract

During inflammation, proteinases are released by inflammatory and tissue cells. The activation of the complement, the coagulation and the fibrinolytic systems produces additional proteinases. Active proteinases become inactivated by various inhibitors in the circulation and tissues. Among the plasma proteinase inhibitors, alpha₁ -antiproteinase and α₂-macroglobulin (α₂M) are most abundant (1). The α₂M-proteinase complexes are removed from the circulation by fixed tissue macrophages in the liver and spleen and broken down (2,3). In the experiments summarized in this paper, we have looked for the presence of α₂M-proteinase complexes in phagocytic cells of synovial tissues and exudates from patients with joint diseases. In parallel, we established that only α₂M-proteinase complexes and not free α₂M or proteinases are taken up by phagocytic cells.