DIFFERENT SELENIUM-CONTAINING PROTEINS IN THE EXTRACELLULAR AND INTRACELLULAR MEDIA OF LEUKOCYTES CULTIVATED IN-VITRO

The purpose of this communication is to elucidate if selenium plays a role in the function of granulocytes and lymphocytes. Thus, the incorp oration of selenium in proteins from granulocytes and lymphocytes cult ured with 1 mu Ci/mL radioactive (Na2SeO3)-Se-75 was studied. The prot ein peaks containing Se-75 from two columns of Heparin Sepharose CL-6B and Sephacryl S-200 HR were separated further by sodium dodecyl sulfa te-polyacrylamide gel electrophoresis (SDS-PAGE) analysis. The results showed that the incorporation of Se-75 into granulocytes was about si x times higher than that of lymphocytes during a 96-h cultivation, how ever, the GSH-Px activity in granulocytes did not change significantly On the other hand, the GSH-Px activity of lymphocytes rose significan tly after three days cultivation. These data indicated that the main c hemical form of selenium in granulocytes was not GSH-Px. Results from SDS-PAGE revealed a strongly Se-75-labeled protein band with subunit m olecular weight of 15 kDa in the supernatant of granulocyte homogenate . However, the main chemical forms of selenium in the culture media of granulocytes and lymphocytes were found to be selenoprotein P. The di fferent forms of selenium-containing proteins in the intracellular and extracellular media of granulocytes indicated the different functions of these proteins.