The effect of calcium channel blocking on immune capacity of cardiovascular patients.

Calcium channel blocking drugs are widely used in the treatment of cardiovascular diseases. In vitro these drugs have been shown to block mitogen-induced lymphocyte proliferation. Their possible immunosuppressive effect has been tested especially in combination with cyclosporine A. In the present work, the effect of the calcium channel blocking drug verapamil on immune functions of cardiovascular patients was studied. The changes in leukocyte subpopulations, mitogenic responses and immunoglobulin production were determined during a three-month therapy. A significant increase in suppressor/cytotoxic cell number was detected and a decrease in the CD4/CD8 ratio, although the values were still within normal range. The responses to T and B cell mitogens remained unchanged. No significant decrease could be detected in immunoglobulin production either, despite minor changes in IgM. Our results indicate that the immunologic effects of verapamil at therapeutic doses are of little clinical significance.