Evidence for voltage modulation of IL-2 production in mitogen-stimulated human peripheral blood lymphocytes.
The membrane potential of human PBMC was modulated in culture by isotonic high extracellular K+ (K+e), or the K+ channel blocker, charybdotoxin (ChTX), to determine the effect of depolarization on stimulated proliferation, IL-2 elaboration, and gene expression. In serum-free cultures, ChTX and high [K+]e induced a specific dose-dependent decrease in IL-2 production. ChTX inhibited proliferation of PBMC and purified T cells, decreased IL-2 elaboration 15 h after stimulation by 78.4 +/- 5.3% (n = 5), and decreased IL-2 mRNA steady-state levels by 80% between 8 and 10 h after stimulation. The IC50 for ChTX-inhibition of IL-2 elaboration and IL-2 mRNA were both 1 nM. Similarly, high [K+]e inhibited proliferation with an IC50 of 38.9 +/- 1.1 mM (n = 13), decreased IL-2 elaboration with an IC50 of 21.3 +/- 1.2 mM (n = 6), and decreased IL-2 mRNA steady-state levels with an IC50 of 18 mM. The sensitivities of both IL-2 production and proliferation to depolarization were substantially reduced by calcium, serum, and exogenous rIL-2. From these findings we conclude that membrane potential may contribute to the control of immune responsiveness in vivo.
D015152:Blotting, Northern; D002118:Calcium / Q000494:pharmacology; D018999:Charybdotoxin; D004305:Dose-Response Relationship, Drug; D015870:Gene Expression / Q000187:drug effects; D006801:Humans; D007376:Interleukin-2 / Q000096:biosynthesis* / Q000494:pharmacology; D008213:Lymphocyte Activation / Q000187:drug effects / Q000276:immunology*; D008214:Lymphocytes / Q000378:metabolism*; D008564:Membrane Potentials / Q000502:physiology*; D010835:Phytohemagglutinins; D011188:Potassium / Q000494:pharmacology; D015221:Potassium Channels / Q000502:physiology; D012333:RNA, Messenger / Q000096:biosynthesis; D011994:Recombinant Proteins / Q000494:pharmacology; D012604:Scorpion Venoms / Q000494:pharmacology; D013997:Time Factors
D007376:Interleukin-2; D010835:Phytohemagglutinins; D015221:Potassium Channels; D012333:RNA, Messenger; D011994:Recombinant Proteins; D012604:Scorpion Venoms; D018999:Charybdotoxin; D011188:Potassium; D002118:Calcium