The role of calmodulin in human natural killer cell activity.

Calcium is known to play an essential role in the lytic mechanism of natural killer cells (NK), which form a subset of large granular lymphocytes. Many of the intracellular effects of calcium are mediated through the calcium-binding protein calmodulin. In this study we have demonstrated that the specific calmodulin inhibitors (naphthalene-sulphonamides) inhibit NK activity in humans at IC50's of 6.9 microM for W7 and 5.2 microM for W13. Comparison of the potency of these compounds with their less active counterparts suggests that NK activity is calmodulin-dependent.