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Urokinase receptor. An activation antigen in human T lymphocytes

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The ability of activated T lymphocytes to extravasate and reach inflammatory and malignant foci in the tissues is a basic function of cellular immunity. Recent evidence strongly suggests that the urokinase receptor (uPAR) holds a central position in the development of human two-chain urokinase-mediated pericellular proteolysis and matrix degradation, an important element in cell migration. In this report we establish uPAR as a pan T cell activation Ag. As determined by FACS analysis, CD3+ lymphocytes from healthy donors exhibited no significant uPAR expression. In contrast, patients (e.g., HIV-positive donors) showed distinct uPAR expression, confined to HLA-DR+ cells, in up to 80% of all T cells. In vitro activation by PMA caused a rapid up-regulation of membrane uPAR in all healthy donor T cells and was accompanied by enhanced receptor synthesis and elevated uPAR mRNA levels. A similar induction resulted from activation via the TCR/CD3 complex using mitogens (PHA, and Con A), anti-CD3 antibodies, and alloantigen. Receptor expression at single cell level was also modulated by a number of cytokines. IL-2, IL-4 and IL-7 increased uPAR presentation on 20 to 50% of the T cell population, and combined stimulation of bulk cultures demonstrated an additive effect of IL-2 and IL-7, whereas the response to each of the two was inhibited by IL-4. In addition, TGF-beta 1 substantially reduced the uPAR expression in T cell cultures responding to PHA, IL-2, and IL-7. Irrespective of the activating reagent, the T cells appeared to produce the same molecular uPAR species, but the affinity of uPAR expressed in PMA blasts was decreased, presumably because of a differential location at the cell surface. All activated cultures showed co-expression of uPAR and CD25. The finding that the urokinase receptor is an activation Ag may suggest that cell-associated plasminogen activation is involved in extravasation and migration of activated T cells.
Original languageEnglish
JournalJournal of Immunology
Pages (from-to)505-16
Number of pages12
Publication statusPublished - 1994

    Research areas

  • Antigens, CD27, Base Sequence, DNA Primers, Gene Expression, Humans, Interleukin-2, Interleukin-4, Interleukin-7, Lymphocyte Activation, Molecular Sequence Data, Phorbol Esters, RNA, Messenger, Receptors, Antigen, T-Cell, Receptors, Cell Surface, Receptors, Urokinase Plasminogen Activator, T-Lymphocyte Subsets, Transforming Growth Factor beta

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