title: Surface membrane CD4 turnover in phorbol ester stimulated T-lymphocytes. Evidence of degradation and increased synthesis.
abstract: Down-regulation of surface membrane CD4 (smCD4) in phorbol ester stimulated T-cells resulted from internalization. Internalization (T1/2 = 15 min at 50 ng PMA/ml) was followed by degradation of CD4-bound antibodies. Degradation in unstimulated T-cells was comparatively insignificant. Release of degradation products was PMA dose-dependent and could be inhibited by methylamine. Uptake and degradation continued after maximal down-regulation of surface membrane CD4, and methylamine did not inhibit reappearance of smCD4 antigens. Metabolic labelling of T-cells further showed that ongoing synthesis rather than recycling contributed to an accelerated smCD4 turnover in activated cells.
authors: Department of Clinical Immunology, University Hospital of Aarhus, Denmark.
authors: B K
authors: BK
authors: Møller
authors: B S
authors: BS
authors: Andresen
authors: E I
authors: EI
authors: Christensen
authors: C M
authors: CM
authors: Petersen
mesh_terms: D000911:Antibodies, Monoclonal; D015704:CD4 Antigens / Q000032:analysis / Q000276:immunology*; D002478:Cells, Cultured; D006801:Humans; D007700:Kinetics; D008213:Lymphocyte Activation; D013601:T-Lymphocytes / Q000187:drug effects / Q000276:immunology*; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology*
chemical_list: D000911:Antibodies, Monoclonal; D015704:CD4 Antigens; D013755:Tetradecanoylphorbol Acetate