EXPRESSION OF TRANSFERRIN RECEPTORS ON MITOGEN-STIMULATED HUMAN PERIPHERAL-BLOOD LYMPHOCYTES - RELATION TO CELLULAR ACTIVATION AND RELATED METABOLIC EVENTS

  • 1 January 1981
    • journal article
    • research article
    • Vol. 44  (4) , 703-710
Abstract
Mitogen-activated normal human peripheral blood lymphocytes bind transferrin to specific membrane receptors. Lymphocytes stimulated with phytohemagglutinin for 0-66 h were examined to determine the relation of this phenomenon to cellular activation and related metabolic events. Transferrin receptors were first detected at 20-24 h. This event was consistently preceded by RNA and protein turnover which commenced during the first 6 h of culture; initiation of DNA synthesis was detected concurrently with the appearance of receptors of slightly later (24-30 h). Exposure of cells to inhibitors of RNA and protein synthesis early during culture (at 0 or 24 h) prevented the expression of transferrin receptors, but also caused generalized metabolic failure and abrogated cellular activation. Later addition of these agents at 48 h did not interfere significantly with the process of activation, but suppressed the terminal increase in receptor-bearing cells observed during the final 18 h in control cultures lacking inhibitor. After deliberate thermal stripping of receptors from activated cells, the reappearance of membrane binding sites which normally occurred within 30 min, was also blocked by cycloheximide, puromycin and actinomycin D. Similar inhibition of DNA induced by hydroxyurea had much less effect upon both the initial appearance of receptors and their reappearance after ligand-induced depletion. The appearance of transferrin receptors upon human lymphocytes is dependent upon cellular activation and requires synthesis of protein and RNA.