Intracellular Ca2+ regulation in CD3 stimulated Jurkat T cells involves H+ fluxes.
Triggering the CD3/TCR complex of T lymphocytes induces a rapid rise in cytosolic free calcium followed by a slowly declining plateau. The level of this plateau depends on external pH, the more alkalinized media leading to higher values. Neither a pH-dependent binding of mAb, nor a perturbation of internal pH can account for this effect. In a sodium-free medium, or in the presence of dimethylamiloride Ca2+, elevation is accompanied by an acidification of the cells; both of them depend, to the same extent, on external calcium concentration. TPA inhibits CD3-, but not ionomycin-induced Ca2+ and H+ raises, indicating that it acts more probably on Ca2+ influx, rather than on its efflux. These results suggest that intracellular calcium could be regulated by a Ca2+/H+ ATPase which drives H+ in and Ca2+ out. In the presence of external Na+, H+ should return to the medium by the Na+/H+ exchanger.
Berthe
P
P
INSERM U210, Faculté de Médecine (Pasteur), Nice, France.
Cousin
J L
JL
Breittmayer
J P
JP
D000945:Antigens, Differentiation, T-Lymphocyte / Q000378:metabolism*; D017252:CD3 Complex; D002118:Calcium / Q000378:metabolism*; D002352:Carrier Proteins / Q000378:metabolism; D002460:Cell Line; D005455:Fluorescent Antibody Technique; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008213:Lymphocyte Activation; D011522:Protons; D011948:Receptors, Antigen, T-Cell / Q000378:metabolism*; D017923:Sodium-Hydrogen Exchangers; D013601:T-Lymphocytes / Q000276:immunology / Q000378:metabolism*; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology
D000945:Antigens, Differentiation, T-Lymphocyte; D017252:CD3 Complex; D002352:Carrier Proteins; D011522:Protons; D011948:Receptors, Antigen, T-Cell; D017923:Sodium-Hydrogen Exchangers; D013755:Tetradecanoylphorbol Acetate; D002118:Calcium