GABA modulates cytotoxicity of immunocompetent cells expressing GABAA receptor subunits

C57 black mouse splenic T lymphocytes effector cells were co-cultivated with Balb/c mouse splenic cells for sensitization; P815 DBA mouse mastocytoma target cells were then added and specific T cell-dependent cytotoxicity determined. This cytotoxicity increased after gamma-aminobutyric acid (GABA) treatment of the sensitized effectors, but decreased after GABA treatment of the targets. These GABA effects seemed to be specific since they were partially mimicked by linear but not ramified GABA analogues. Furthermore, they were likely mediated by GABAA receptor since GABAA receptor subunit mRNAs and protein could be demonstrated in effector or target immune specific cells, suggesting that under yet to be defined circumstances, GABA may affect T cell functions.