EXCITATORY SODIUM CURRENTS OF NH15-CA2 NEUROBLASTOMA X GLIOMA HYBRID-CELLS ARE DIFFERENTLY AFFECTED BY INTERLEUKIN-2 AND INTERLEUKIN-1-BETA

The neuroblastoma x glioma hybrid cell. line NH15-CA2 was used to test the effects of two interleukins on neuronal Na+ channels. The cells w ere cultured in the presence of dibutyryl cAMP and retinoic acid, whic h yielded a high expression of Na+ channels so that the cells were exc itable. Na+ currents were triggered and recorded in the whole-cell rec ording mode. Comparison of the effects of tetrodotoxin and mu-conotoxi n established that the expressed Na+ channels were of the neuronal typ e. Bath-applied recombinant human interleukin-2 (rIL-2) had a reversib le inhibitory effect on the Na+ currents, although to a lesser extent than on muscular Na+ currents (more than 1000 U/ml required for 50% bl ock in NH15-CA2 cells vs 500 U/ml in myoballs). The current/voltage re lationship was not affected by the presence of rIL-2, but the steady-s tate inactivation curve was shifted by -7.7 +/- 4.8 mV (mean +/- SD, n =18). Recombinant human interleukin-1 beta (rIL-1 beta), applied at 10 00 U/ml, showed an inhibitory effect on the Na+ currents in about one- third of the cells tested. The mechanism of inhibition was different f rom that of rIL-2, as rIL-1 beta seemed to cause a block without affec ting voltage dependence or kinetics of the channels.