title: Cultured human monocytes synthesize and secrete alpha2-macroglobulin.
abstract: alpha2-Macroglobulin levels in the supernates of cultures of different subpopulations of human peripheral blood mononuclear leukocytes were assayed by a radioimmunoassay. Unfractionated mononuclear leukocytes produced greater amounts of the macroglobulin (4.0 vs. 0.8 ng/10(6) cells) than did subpopulations enriched in T or B+T lymphocytes, by passage through nylon wool or cotton wool columns, respectively. Still higher concentrations of alpha2-macroglobulin (40 ng/10(6) cells) were measured in the supernates of glass-adherent mononuclear leukocyte cultures. These results suggest that cells of monocyte-macrophage lineage are mainly, if not exclusively, responsible for the appearance of alpha2- macroglobulin in the supernate of human peripheral blood leukocyte cultures. The de novo synthesis and release of alpha2-macroglobulin by cultured monocytes was demonstrated by immunoprecipitation of radioactivity from supernates of 32S-methionine-labeled glass-adherent cells. Antiserum against purified alpha2-macroglobulin was used in both Ouchterlony double diffusion and double antibody precipitation tests. SDS-polyacrylamide gel electrophoresis of immunoprecipitates showed that most of the radioactivity comigrated with authentic alpha2-macroglobulin subunit at about 160,000 daltons.
mesh_terms: D001402:B-Lymphocytes / Q000378:metabolism; D002478:Cells, Cultured; D011232:Chemical Precipitation; D004591:Electrophoresis, Polyacrylamide Gel; D005455:Fluorescent Antibody Technique; D006801:Humans; D007962:Leukocytes / Q000378:metabolism; D008264:Macrophages / Q000378:metabolism; D009000:Monocytes / Q000378:metabolism*; D010455:Peptides / Q000378:metabolism; D000511:alpha-Macroglobulins / Q000096:biosynthesis* / Q000378:metabolism
chemical_list: D010455:Peptides; D000511:alpha-Macroglobulins