The Role of Calcium in Stimulation of Activated T Lymphocytes with Interleukin 2

In a study of the role of Ca in the stimulation of activated T lymphocytes with interleukin 2 (IL‐2) it was found that IL‐2‐induced proliferation can occur independently of extracellular calcium. Further, there was no correlation between triggering of DNA synthesis and an increase in free cytoplasmic calcium. However. IL‐2 induced an increased uptake of 45Ca from the extracellular medium. Since there is no increase in free cytoplasmic calcium, it must be assumed that this is caused by an increase in membrane‐associated calcium. Further, the calcium channel‐blocking agent, verapamil, and TMB‐8, a putative inhibitor of mobilization of calcium from intracellular pools, both exerted a dose‐dependent inhibition of IL‐2‐induced DNA synthesis in activated T lymphocytes. We conclude that calcium is not a second messenger in activated T lymphocytes stimulated by IL‐2, but our results indicate that calcium may play a role at membrane level.