Chloride-channel block inhibits T lymphocyte activation and signalling

Cell Signal. 1996 Feb;8(2):141-9. doi: 10.1016/0898-6568(95)02039-x.


Both large- and small-conductance chloride (Cl-) channels have been found in human T lymphocytes; however, apart from possible roles in mediating regulatory volume decrease, their functions are not understood. We have used patch-clamp electrophysiology, Ca2+ spectrofluorometry, and Western blot assay for phosphotyrosine to investigate the effects of blocking Cl- channels on proliferation and on specific events in the activation of normal human T cells. Four chemically distinct Cl- channel blockers inhibited both the small-conductance Cl- channels and phytohemagglutinin (PHA)-induced lymphocyte proliferation in a similar dose-dependent manner; their order of potency was 5-nitro-2(3-phenylpropylamino)-benzoic acid (NPPB) > 4,4'-diisothiocyano-2,2'-disulfonic acid (DIDS) > flufenamic acid >> IAA-94. The Cl- channel blockers inhibited both the PHA-induced mobilization of Ca2+ and the rapid tyrosine phosphorylation of several polypeptides. Cell proliferation was not rescued by the Ca+ ionophore ionomycin or by addition of exogenous interleukin-2 (IL-2). Moreover, the blockers also inhibited phosphotyrosine expression in IL-2-treated, activated lymphoblasts. Thus, our results support a role for Cl- channels in early, PHA-evoked signalling and in later, II-2-dependent stages of lymphocyte activation and proliferation.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Blotting, Western
  • Calcium / physiology
  • Cell Division / drug effects
  • Cell Division / immunology
  • Chloride Channels / antagonists & inhibitors*
  • Dose-Response Relationship, Immunologic
  • Humans
  • Immunosuppressive Agents / pharmacology
  • Interleukin-2 / pharmacology
  • Lymphocyte Activation / physiology*
  • Patch-Clamp Techniques
  • Phosphorylation
  • Signal Transduction / immunology*
  • Spectrometry, Fluorescence
  • T-Lymphocytes / chemistry
  • T-Lymphocytes / cytology
  • T-Lymphocytes / physiology*
  • Tyrosine / metabolism


  • Chloride Channels
  • Immunosuppressive Agents
  • Interleukin-2
  • Tyrosine
  • Calcium