High-throughput profiling of ion channel activity in primary human lymphocytes

We present a high-throughput method to quantify the functional activity of potassium (K⁺) ion channels in primary human lymphocytes. This method is rapid, automated, specific (here for the voltage-gated Kv1.3 ion channel), and capable of measuring, in parallel, the electrical currents of over 200 individual lymphocytes isolated from freshly drawn blood. The statistics afforded by high-throughput measurements allowed direct comparison of Kv1.3 activity in different subsets of lymphocytes, including CD4⁺ and CD8⁺ T cells, γδ T cells, and B cells. High-throughput measurements made it possible to quantify the heterogeneous, functional response of Kv1.3 ion channel activity upon stimulation of CD4⁺ and CD8 ⁺ T cells with mitogen. These experiments enabled elucidation of time-courses of functional Kv1.3 activity upon stimulation as well as studies of the effects of the concentration of mitogenic antibodies on Kv1.3 levels. The results presented here suggest that Kv1.3 ion channel activity can be used as a functional activation marker in T cells and that it correlates to cell size and levels of a surface antigen, CD25. Moreover, this work presents an enabling methodology that can be applied widely, allowing high-throughput screening of specific voltage-gated ion channels in a variety of primary cells.