Expression of tumor necrosis factor receptors on human monocytes and internalization of receptor bound ligand.
Tumor necrosis factor (TNF) is a polypeptide produced by monocytes and macrophages. Although TNF receptors have been identified on a variety of cell types, previous studies have not determined whether these receptors also exist on monocytes. In the present work, highly purified recombinant TNF was labeled with 125I. The 125I-labeled TNF bound specifically to receptors on human monocytes and monocyte membrane preparations. A curvilinear Scatchard plot indicated the presence of TNF-binding sites with two different affinities. The results also indicate that receptor-bound TNF is rapidly internalized by monocytes and then degraded intracellularly. These findings are in concert with recent studies demonstrating that TNF immunomodulates monocyte function by an autocrine mechanism.
Imamura
K
K
Laboratory of Clinical Pharmacology, Dana-Farber Cancer Institute, Harvard Medical School, Boston, MA 02115.
Spriggs
D
D
Kufe
D
D
D001665:Binding Sites; D002462:Cell Membrane / Q000378:metabolism; D004705:Endocytosis; D006801:Humans; D008024:Ligands; D009000:Monocytes / Q000378:metabolism*; D011956:Receptors, Cell Surface / Q000378:metabolism*; D018124:Receptors, Tumor Necrosis Factor; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism*
D008024:Ligands; D011956:Receptors, Cell Surface; D018124:Receptors, Tumor Necrosis Factor; D014409:Tumor Necrosis Factor-alpha