T cell activation through Thy-1 is associated with the expression of a surface protein(p100) on a subset of CD4 cells

Academic Article


  • Thy-1 molecules, which lack a transmembrane domain, can nonetheless induce T cell activation; it has thus been suggested that a separate transmembrane molecule associated with Thy-1 is required for signal transduction. We have previously characterized a transmembrane protein with an Mr of 100,000 (p100), which is non-covalently bound to two glycosyl-phosphatidylinositol (GPI)-linked molecules, Thy-1 and ThB. p100 is selectively expressed on the T cell surface and divides peripheral CD4 cells into two subpopulations. This differential expression on CD4 cells allowed us to investigate the role of p100 in signal transduction through Thy-1 molecules. Here we report that only p100+ CD4 cells proliferate and release cytokines in response to cross-linkage of Thy-1, although both p100+ and p100- CD4 cells strongly express Thy-1 on their surfaces. Control stimulation by anti-CD3 antibodies or concanavalln A induces identical thymidine uptake by the two CD4 cell populations. Interestingly, these two populations of CD4 cells had different cytokine release profiles after activation through CD3: only p100+ CD4 cells released high amounts of IL-2 and IFN-γ, whereas both populations released IL-4. p100 expression correlates with the induction of homotypic aggregation of T cells after Thy-1 triggering. p100 is associated with kinase activity (fyn and lck), and phosphorylated proteins of 90, 59, 57 and 33 kDa co-precipitate with Thy-1 only in p100+ CD4 cells. Altogether, these data suggest that p100 is involved in signal transduction through Thy-1. p100 expression by activated CD4 cells in vivo may be relevant to the proposed function of Thy-1 as an accessory signaling molecule in cell activation. © 1995 Oxford University Press.
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    Digital Object Identifier (doi)

    Author List

  • Lehuen A; Beaudoin L; Bernard M; Kearney JF; Bach JF; Monteiro RC
  • Start Page

  • 607
  • End Page

  • 616
  • Volume

  • 7
  • Issue

  • 4