Interaction between Cl^- channels and CRAC-related Ca²⁺ signaling during T lymphocyte activation and proliferation

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 ConAinduced 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 ConAinduced 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 DIDSsensitive Cl^– channels may be related to the ClC-3 Cl^– channels.