Cigarette smoke extract acts directly on CD4 T cells to enhance Th1 polarization and reduce memory potential.

•Cigarette smoke extract reduces division and increases apoptosis of Th1 effectors.•Cigarette smoke extract enhances Th1 cytokine production and T-bet expression.•Cigarette smoke extract mediates its impact directly on responding CD4 T cells.•Cigarette smoke extract drives terminal differentiation and restricts memory fate.