Thapsigargin Increases IL-2 Production in T Cells at Nanomolar Concentrations

Thapsigargin (TGN) is a potent and selective inhibitor of sarco-endoplasmic Ca²⁺-ATPase, leading to rapid elevation of cytoplasmic Ca²⁺ concentration. Previous reports have shown that TGN increases the production of various cytokines from macrophages and dendritic cells. Here, we examine the effects of TGN on murine T cells. Nanomolar concentrations of TGN are a significant inducer of IL-2 production with full activity at 50 nM. Micromolar concentrations of TGN, however, are inhibitory to IL-2 production and T cell proliferation. The IL-2 production-inducing activity of TGN is much more prominent when T cells are primed with concanavalin A or anti-CD3 mAb, and is due to the increase of cytoplasmic Ca²⁺ concentration. TGN at 50 nM does not affect interferon-gamma or IL-4 production from T cells. Thus, the present study shows that low nanomolar concentrations of TGN could be useful in potentiating IL-2 production from antigen-primed T cells.