Inhibition of T cell proliferation by selective block of Ca 2+ -activated K + channels
Open Access
- 14 September 1999
- journal article
- research article
- Published by Proceedings of the National Academy of Sciences in Proceedings of the National Academy of Sciences
- Vol. 96 (19), 10917-10921
- https://doi.org/10.1073/pnas.96.19.10917
Abstract
T lymphocytes express a plethora of distinct ion channels that participate in the control of calcium homeostasis and signal transduction. Potassium channels play a critical role in the modulation of T cell calcium signaling, and the significance of the voltage-dependent K channel, Kv1.3, is well established. The recent cloning of the Ca2+-activated, intermediate-conductance K+ channel (IK channel) has enabled a detailed investigation of the role of this highly Ca2+-sensitive K+ channel in the calcium signaling and subsequent regulation of T cell proliferation. The role IK channels play in T cell activation and proliferation has been investigated by using various blockers of IK channels. The Ca2+-activated K+ current in human T cells is shown by the whole-cell voltage-clamp technique to be highly sensitive to clotrimazole, charybdotoxin, and nitrendipine, but not to ketoconazole. Clotrimazole, nitrendipine, and charybdotoxin block T cell activation induced by signals that elicit a rise in intracellular Ca2+—e.g., phytohemagglutinin, Con A, and antigens such as Candida albicans and tetanus toxin in a dose-dependent manner. The release of IFN-γ from activated T cells is also inhibited after block of IK channels by clotrimazole. Clotrimazole and cyclosporin A act synergistically to inhibit T cell proliferation, which confirms that block of IK channels affects the process downstream from T cell receptor activation. We suggest that IK channels constitute another target for immune suppression.Keywords
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