Acta Pharmacologica Sinica 2006 April; 27 (4): 437-446; doi: 10.1111/j.1745-7254.2006.00297.x

Aim: To test the hypothesis that Cl^- channel blockers affect T cell proliferation through Ca²⁺-release-activated Ca²⁺ (CRAC) signaling and examine the effects of the combination of a CRAC channel blocker and a Cl^- channel blocker on concanavalin A (ConA; 5 mg/mL)-induced Ca²⁺ signaling, gene expression and cellular proliferation in human peripheral T lymphocytes.

Methods: [³H]Thymidine incorporation, Fura-2 fluorescent probe, RNase protection assay, and reverse transcription-polymerase chain reaction were used.

Results: The Cl^- channel blocker 4,4'-diisothiocyanostilbene-2,2'-disulfonic acid (DIDS) inhibited ConA-induced Ca²⁺ influx, interleukin-2 mRNA expression and T lymphocyte proliferation in a concentration-dependent manner, and also enhanced the inhibitory effects of 1-{beta-[3-(4-methoxyphenyl)propoxyl]-4-methoxyphenethyl}-1H-imidazole (SK&F96365) on the above key events during T cell activation. A combination of DIDS (1 µmol/L) and SK&F96365 (1 µmol/L) significantly diminished ConA-induced ClC-3 mRNA expression by 64%, whereas DIDS (1 µmol/L) or SK&F96365 (1 µmol/L) alone decreased ConA-induced ClC-3 mRNA expression by only 16% and 9%, respectively.

Conclusion: These results suggest that there is an interaction between CRAC-mediated Ca²⁺ signaling and DIDS-sensitive Cl^- channels during ConA-induced T cell activation and proliferation. Moreover, the DIDS-sensitive Cl^- channels may be related to the ClC-3 Cl^- channels.

Keywords: T lymphocytes; lymphocyte activation; chloride channels; calcium; ion channels; interleukin-2