title: The significance of 125I as a tracer for lymphocytes, liver cells and erythrocytes after iodination by the lactoperoxidase-H2O2 technique.
abstract: Human erythrocytes, porcine and rat liver cells, porcine spleen lymphocytes and cultured human lymphoma cells (266 Bl) have been labelled with 125I by the lactoperoxidase-H2O2 method. Large amounts of radioactivity were released when the iodinated cells were incubated in different buffers, and the rate of the release varied considerably between the different cells. Incubation at a higher temperature increased the release rate, while metabolic inhibitors such as iodoacetamide, trasylol or sodium azide did not. When collagenase was used during the preparation of spleen lymphocytes, the rate of the radioactivity release was decreased about 50%. Several findings indicated that the released radioactivity originated from free iodide. When the labelled lymphocytes were treated with a nonionic detergent, Nonidet P-40, 90% of the total radioactivity was solubilized. Only 10-15% of the radioactivity was stably bound in macromolecular material. The remaining part, corresponding to the amount of radioactivity released during incubation, was shown to be free iodide. It is concluded that the significance of the 125I-label in living cells has to be studied in each case at the specific experimental conditions used. After the unspecifically trapped iodide is released--normally after about 2 h--the label is considered to be useful for studies with intact cells.
mesh_terms: D000818:Animals; D003902:Detergents / Q000494:pharmacology; D004912:Erythrocytes / Q000378:metabolism*; D006801:Humans; D007124:Immunoenzyme Techniques; D007454:Iodides / Q000032:analysis; D007457:Iodine Radioisotopes / Q000032:analysis*; D007700:Kinetics; D008099:Liver / Q000378:metabolism*; D008214:Lymphocytes / Q000378:metabolism*; D051381:Rats; D013552:Swine
chemical_list: D003902:Detergents; D007454:Iodides; D007457:Iodine Radioisotopes