Regulated expression of galectin-1 during B-cell activation and implications for T-cell apoptosis

Galectin-1 (GAL-1), a highly conserved beta -galactoside-binding protein, h as shown immunomodulatory properties. In this study, we investigated the re gulation of GAL-1 expression within the B-cell compartment using Trypanosom a cruzi infection as a natural model of in vivo B-cell activation. GAL-1 wa s found to be expressed on activated B cells from T. cruzi-infected mice, m ainly localized at the cytosolic compartment. Expression of this protein wa s found to be modulated according to the activation state of the cells, rev ealing a significant increase in stimulated B cells that received signals v ia cross-linking of the B-cell receptor and CD40. It was found that GAL-1 w as secreted by B cells to the extracellular milieu upon activation. Finally , purified GAL-1 produced by activated B cells induced apoptosis of T cells but not B cells and also influenced interferon-gamma cytokine production. Hence, the present study describes a potential mechanism by which B cells c an regulate T-cell function and survival.