Expression and function of galectin-3, a beta-galactoside-binding protein in activated T lymphocytes.

A soluble beta-galactoside-binding lectin, galectin-3 has been shown to be involved in cell adhesion and activation of immune cells. Although galectin-3 is known to be expressed in various types of cells, it has not been shown whether galectin-3 is expressed in T lymphocytes. We present evidence here that galectin-3 is expressed in activated murine T lymphocytes including CD4+ and CD8+ T cells but not in resting T cells. Galectin-3 expression was induced by anti-CD3 mAb or mitogen and enhanced by common gamma-chain signaling cytokines, IL-2, IL-4, and IL-7, in activated T lymphocytes, whereas the inflammatory cytokines including TNF-alpha and IFN-gamma did not. Galectin-3 expression and proliferation were down-regulated by withdrawal of IL-2 and gamma irradiation. Antisense but not sense phosphorothioated oligonucleotides for galectin-3 inhibited galectin-3 expression and blocked proliferation of T cells significantly. This study suggests that up-regulation of galectin-3 plays an important role in proliferation of activated T lymphocytes.