Interleukin-2 inhibits sodium currents in human muscle cells.

The effect of the T cell growth factor interleukin-2 (IL-2) on muscular Na+ channels was studied in myoballs produced from primary human muscle cultures. The transient Na+ inward currents of the myoballs, elicited by repetitive stimulation at 1 Hz and recorded in the whole-cell mode, were inhibited by IL-2 applied to the external solution, the half maximum effect occurring at 300 U/ml. The effect was complete within 5 s and was totally reversible, the on and off effects having identical time courses. The h infinity curve was shifted in negative direction indicating that the mechanism of IL-2 action is a conversion of the Na+ channels into a state of inactivation. The reaction of the IL-2 solution with an anti IL-2 antibody neutralized the inhibitory effect on the Na+ currents, indicating a specific effect of the peptide growth factor interleukin-2 on muscular Na+ channels. The connection of IL-2 and Na+ channels may be important in inflammatory processes of muscle and nerve.