Throughout development, CD4+T cells fate decisions are converted into epigenetic information that determines cellular identity.Covalent histone modifications mediated by lysine-specific demethylase 1(LSD1) are heritable epigenetic marks and are hypothesized to occupy an important central role in this process.This study was conducted to evaluate the direct effects of LSD1 chemic inhibitor (TCP, tranylcypromine) on helper T lymphocytes (Th) from healthy donors.