The Anti-Proliferative Effect of Cation Channel Blockers on T Lymphocytes Stimulated by Anti-CD3 and Anti-CD28

Abstract

The ion channels of T lymphocytes form a crucial part of the healthy immune system, as they are important for cellular activation and proliferation. In autoimmune diseases, effector memory T cells have a unique ion channel pattern, therefore they are promising therapeutic targets. A number of ion channel inhibitors are known as selective inhibitors of T lymphocyte proliferation, but the data available is contradictory. Our aim was to elucidate this phenomenon by investigating how the blockage of ion channels affects the activation and proliferation of T cells treated previously with different concentrations of mitogens.In our experiments human peripheral blood lymphocytes from volunteers were activated via monoclonal antibodies affecting the TCR-CD3 complex on the cell surface and the co-stimulator molecule CD28. We applied specific ion channel blockers acting on the major cationic channels of the T cell, the Kv1.3, the KCa1.1 and the CRAC channel, either alone or in combination with rapamycin, the inhibitor of the mammalian target of rapamycin (mTOR). Five days after the stimulus flow cytometry measurements were performed to determine the extent of cellular viability and proliferation.Our measurements indicated that ion channel blockers and rapamycin had a negative dose-dependent effect on the amount of cell division. Simultaneous application of blockers for each channel along with rapamycin proved to be the most effective, which indicates that they affect independent regulation pathways. Upon increasing the rate of stimulation, the anti-proliferative effect of the blockers diminished. This phenomenon was unknown to date and may prove to be important in understanding the fine-tuning of T cell activation.