Verapamil inhibition of lymphocyte proliferation and function in vitro.

Calcium is a divalent cation which acts both as a cofactor for critical protein function and as a "second signal" to trigger cytosol events after membrane depolarization. The presence of calcium is critical to T-lymphocyte function. Verapamil is a calcium channel blocker at the membrane level and may affect cytosol calcium-calmodulin as well. Verapamil effect was measured on two assays of lymphocyte proliferation (concanavalin A and phytohemagglutinin lectin and alloantigen stimulated) and on cell-mediated cytotoxicity. Verapamil inhibited proliferation at 10(-5) M doses and abrogated it at 10(-4) M. Verapamil interferes with critical calcium-mediated events in T lymphocyte proliferation and function. T-lymphocyte calcium channel blockade may be an effective immunosuppressive strategy.