Determination of subpopulations of leukocytes involved in the synthesis of alpha 1-antitrypsin in vitro.

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SummaryCell-free culture medium from stimulated and unstimulated 6-day cultures of mononuclear leukocytes (MNL), nonadherent MNL (lymphocytes), and adherent MNL (monocytes) was evaluated for evidence of in vitro synthesis of protein and of α1-antitrypsin (A1AT). Phytohemagglutinin (PHA, 2.0 μg/ml) promoted significant increases in 3H-labeled protein content in both MNL and lymphocyte cultures, whereas endoxotin (25.0 μg/ml) but not PHA caused significant increases in the amount of protein synthesized by monocytes. A1AT was found to be made by MNL and monocytes in culture but was not newly synthesized by lymphocytes. Evidence for the presence of de novo synthesized A1AT was obtained by Sephadex G-200 chromatography, immuno-precipitation with antibody specific for A1AT, and SDS-polyacrylamide gel electrophoresis. Evidence was also found for the release of small amounts of A1AT from the surface of lymphocytes after 6 days in culture, presumably complexed to labeled protease; however, this accounted for less ...