The interference of T cell activation by calcium channel blocking agents.

Calcium has been identified as having an important role as a transmembrane messenger in the activation signal for lymphocytes. To additionally examine this model, we evaluated the effect of calcium channel blocking drugs (verapamil, nifedipine, and diltiazem) on lymphocyte activation. In these studies we found that the drugs inhibit, in a dose-dependent fashion, the proliferation of T cells and the appearance of certain activation antigens after mitogen stimulation. This appears to result from the marked decrease in mitogen-induced 45calcium (45Ca+2) influx secondary to the addition of these agents. In addition, T cell proliferation resulting from IL 2 binding to its receptor is also suppressed by the calcium channel blocking drugs. These data suggest that the passive calcium channel plays a pivotal role in both the initial activation of T cells after ligand-receptor interaction and the ongoing signal for proliferation provided by IL 2 binding to its receptor.