Degradation of solubilized [3H]elastin by intact human monocytes stimulated by immune complexes in vitro

A simple assay is described that permits determination of elastolytic activity released from human monocytes. The substrate, solubilized [3H]elastin, is coated onto cell culture dishes. Blood monocytes are allowed to adhere, and during subsequent serum-free culture, radioactive degradation products of elastolysis are released into the culture medium. Using this assay we have demonstrated an elastolytic activity by normal human monocytes of 20 +/- 2 ng elastin/hour/3 X 10(6) mononuclear cells. Contaminating granulocytes and lymphocytes do not cause any significant elastolysis. On stimulation with immune complexes in vitro, the monocytes respond with an enzymatic burst that is 3.6 times the basic enzyme activity. This assay could be a useful tool in the evaluation of elastolytic activity of cells from other sources as well as from human monocytes.