Differential effect on TCR:CD3 stimulation of a 90-kD glycoprotein (gp90/Mac-2BP), a member of the scavenger receptor cysteine-rich domain protein family

Clin Exp Immunol. 1998 Sep;113(3):394-400. doi: 10.1046/j.1365-2249.1998.00654.x.


We studied the effects of a 90-kD glycoprotein (gp90/Mac-2BP) belonging to the scavenger receptor family, present in normal serum and at increased levels in inflammatory disease and cancer patients, on some T cell function parameters. Whereas the lymphocyte proliferative response to non-specific mitogens such as phytohaemagglutinin (PHA) and concanavalin A (Con A), but not pokeweed mitogen (PWM), was strongly reduced, probably due to the lectin-binding properties of gp90/Mac-2BP, the response to T cell receptor (TCR) agonists such as superantigens and allogeneic cells was potentiated. When lymphocytes were stimulated with different anti-TCR:CD3 MoAbs, both in soluble and solid-phase form, gp90/Mac-2BP was able to down-regulate the proliferative response to anti-CD3 MoAb, whereas the response to anti-TCR alphabeta MoAb was enhanced. A similar differential effect was observed when a MoAb against CD5 (another member of the scavenger receptor superfamily) was added to anti-CD3 or anti-TCR-stimulated cells; anti-CD5 MoAb strongly down-modulated the CD3-mediated response, whereas its presence in culture was associated with potentiation of the response to TCR alphabeta agonists. gp90/Mac-2BP was able per se to up-regulate Ca2+ levels in freshly isolated lymphocytes; moreover, its presence in culture was associated with increased Ca2+ mobilization following stimulation with anti-TCR alphabeta, but not anti-CD3 MoAb. These data indicate that gp90/Mac-2BP could be able to influence some immune responses, possibly through multiple homologous interactions with other members of the scavenger receptor family; moreover, our findings suggest that signalling through the different components of the TCR:CD3 complex may follow distinct activation pathways into the cells.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • 3T3 Cells
  • Animals
  • Antibodies, Monoclonal / immunology
  • Antigens, Differentiation / metabolism*
  • CD5 Antigens / physiology
  • Calcium / metabolism
  • Galectin 3
  • Lymphocyte Activation
  • Membrane Proteins*
  • Mice
  • Molecular Weight
  • Receptor-CD3 Complex, Antigen, T-Cell / physiology*
  • Receptors, Immunologic / physiology*
  • Receptors, Lipoprotein*
  • Receptors, Scavenger
  • Scavenger Receptors, Class B


  • Antibodies, Monoclonal
  • Antigens, Differentiation
  • CD5 Antigens
  • Galectin 3
  • Membrane Proteins
  • Receptor-CD3 Complex, Antigen, T-Cell
  • Receptors, Immunologic
  • Receptors, Lipoprotein
  • Receptors, Scavenger
  • Scarb1 protein, mouse
  • Scavenger Receptors, Class B
  • Calcium