GABA, a natural immunomodulator of T lymphocytes

gamma-aminobutyric acid (GABA) is the main neuroinhibitory transmitter in the brain. Here we show that GABA in the extracellular space may affect the fate of pathogenic T lymphocytes entering the brain. We examined in encephalitogenic T cells if they expressed functional GABA channels that could be activated by the low (nM-1 mu M), physiological concentrations of GABA present around neurons in the brain. The cells expressed the alpha 1, alpha 4, beta 2, beta 3, gamma 1 and delta GABAA channel subunits and formed functional, extrasynaptic-like GABA channels that were activated by 1 mu M GABA. 100 nM and higher GABA concentrations decreased T cell proliferation. The results are consistent with GABA being immunomodulatory. (C) 2008 Elsevier B.V. All rights reserved