title: In vivo fate of 125I SS-B (La) injected into mice.
abstract: The fate of the radiolabelled soluble cellular antigen SS-B (La) was compared with that of other 125I-labelled proteins of known molecular weight (MW) and electrostatic charge, following i.v. injection into BALB/c mice. The plasma half-life of 125I-SS-B was 3 min, while that of 125I-bovine serum albumin (similar MW and electrostatic charge) was 270 min. 125I-heat-aggregated IgG (MW greater than 1 x 10(6)) and 125I-7S human IgG (MW 168,000) had plasma half-lives of 40 min and greater than 300 min, respectively. Liver and kidney showed preferential uptake of 125I-SS-B, followed by a rapid decrease in radioactivity. During this time low MW, trichloroacetic acid (TCA) soluble, material appeared in urine. This suggests a specific uptake mechanism followed by a catabolic phase. These studies demonstrate that normal mice remove 125I-SS-B rapidly from the circulation and then degrade it. This rapid antigen elimination may protect against the induction of potentially harmful autoantibody responses.
mesh_terms: D000818:Animals; D000941:Antigens / Q000032:analysis*; D001324:Autoantigens; D006207:Half-Life; D007074:Immunoglobulin G / Q000378:metabolism; D007457:Iodine Radioisotopes; D008657:Metabolic Clearance Rate; D051379:Mice; D008807:Mice, Inbred BALB C; D012261:Ribonucleoproteins; D012710:Serum Albumin, Bovine / Q000378:metabolism; D014018:Tissue Distribution; D014238:Trichloroacetic Acid / Q000494:pharmacology; D000097585:SS-B Antigen
chemical_list: D000941:Antigens; D001324:Autoantigens; D007074:Immunoglobulin G; D007457:Iodine Radioisotopes; D012261:Ribonucleoproteins; D012710:Serum Albumin, Bovine; D014238:Trichloroacetic Acid; D000097585:SS-B Antigen