Mini-review Potassium channels in T lymphocytes: toxins to therapeutic immunosuppressants

Patch clamp studies in the early eighties revealed the existence of a voltage-gated K1 (Kv) channel in human lymphocytes that resembled delayed recti®er K1 channels in electrically excitable cells (DeCoursey et al., 1984; Matteson and Deutsch, 1984; Cahalan et al., 1985; Schlich-ter et al., 1986). Classical neuronal K1 channel blockers (4-aminopyridine, tetraethylammonium and quinine) and clas-sical calcium channel blockers (verapamil, diltiazem and nifedipine) blocked this channel at micromolar to millimo-lar concentrations (Chandy et al., 1984; DeCoursey et al., 1984; Sabath et al., 1986). Despite having widely differing structures, these compounds inhibited cytokine production and T-cell proliferation with a potency parallel to channel block. The fact that these agents were not cytotoxic, acted reversibly, inhibited only if administered within the ®rs