Elastase of U-937 Monocytelike Cells: COMPARISONS WITH ELASTASES DERIVED FROM HUMAN MONOCYTES AND NEUTROPHILS AND MURINE MACROPHAGELIKE CELLS |
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| Authors: | Robert M. Senior Edward J. Campbell Jill A. Landis Fraya R. Cox Charles Kuhn Hillel S. Koren |
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| Affiliation: | Department of Medicine, Washington University School of Medicine, St. Louis, Missouri 63110;Department of Pathology, Washington University School of Medicine, St. Louis, Missouri 63110;Pulmonary Division, Department of Medicine, The Jewish Hospital of St. Louis, St. Louis, Missouri 63110;Division of Immunology, Department of Medicine, Duke University Medical Center, Durham, North Carolina 27710 |
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| Abstract: | As an approach to facilitating the understanding of proteinases associated with monocytes we have studied U-937 monocytelike cells. Elastase activity was identified in U-937 cell extracts and compared to monocyte elastase activity, neutrophil elastase, and the elastase activity from a continuous line of murine macrophagelike cells (P388D1). Serine proteinase activity which solubilized 14C-labeled elastin accounted for >90% of the neutral proteinase activity of both U-937 cells and monocyte extracts. U-937 cell and monocyte elastase activities were similar catalytically, resembling neutrophil elastase. U-937 cells and monocytes showed other similarities: (a) both had activities reacting with [3H]diisopropylfluorophosphate that migrated in sodium dodecyl sulfate (SDS) polyacrylamide gels at ~30,000 and 60,000 daltons and (b) both contained material that cross-reacted with antiserum raised to neutrophil elastase. Preliminary characterization of U-937 cell elastase activity by affinity chromatography and ion-exchange chromatography suggested the presence of at least two distinct elastases. Minimal elastase activity was found in U-937 cell-conditioned medium, indicating that the activity is not spontaneously released by the cells. In contrast to the elastase activity associated with U-937 cells and monocytes, the elastase activity associated with P388D1 cells was a metalloproteinase and was found principally in the culture medium. These results indicate (a) U-937 cells will be useful for further investigation of proteinases associated with normal monocytes; (b) monocytes and U-937 cells contain material with catalytic and immunologic similarities to neutrophil elastase; (c) monocyte elastase activity differs from elastase activity secreted by murine macrophages and murine macrophagelike cells of the P388D1 line. |
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