The uptake and digestion of iodinated human serum albumin by macrophages in vitro.
Mouse peritoneal macrophages take up I*-HSA from their medium during in vitro cultivation. Conditions which promote I*-HSA uptake are the same as those which stimulate formation of pinocytic vesicles. Autoradiography of cells pulsed with (125)I-HSA showed that intracellular isotope is localized in perinuclear granules, or secondary lysosomes. Following a pulse of (125)I-HSA, intracellular radioactivity decreases and the amount of TCA-soluble isotope in the medium increases correspondingly. About 50% of the intracellular isotope is lost in 5 hr. The release of isotope from pulsed cells is not inhibited by parafluorophenylalanine, 2,4-dinitrophenol or by a reduction of the serum concentration of the medium. However, the processing of ingested (125)I-HSA is reversibly inhibited by reduced temperature. The TCA-soluble radioactive material excreted by pulsed macrophages was identified as monoiodotyrosine.
D000818:Animals; D001345:Autoradiography; D002854:Chromatography, Paper; D046508:Culture Techniques; D008247:Lysosomes / Q000502:physiology; D008264:Macrophages / Q000378:metabolism*; D051379:Mice; D009698:Nucleoproteins / Q000494:pharmacology; D010873:Pinocytosis; D012709:Serum Albumin / Q000378:metabolism*; D012711:Serum Albumin, Radio-Iodinated
D009698:Nucleoproteins; D012709:Serum Albumin; D012711:Serum Albumin, Radio-Iodinated