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

Galectin‐1 (GAL‐1), a highly conserved β‐galactoside‐binding protein, has shown immunomodulatory properties. In this study, we investigated the regulation of GAL‐1 expression within the B‐cell compartment using Trypanosoma cruzi infection as a natural model of in vivo B‐cell activation. GAL‐1 was found to be expressed on activated B cells from T. cruzi ‐infected mice, mainly localized at the cytosolic compartment. Expression of this protein was found to be modulated according to the activation state of the cells, revealing a significant increase in stimulated B cells that received signals via cross‐linking of the B‐cell receptor and CD40. It was found that GAL‐1 was 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‐γ cytokine production. Hence, the present study describes a potential mechanism by which B cells can regulate T‐cell function and survival.