CTLA4 and Huntington disease: In HD (Fig. 3a, b), the expression of inhibitory receptors 2B4 and PD-1 was confined to TEM (mean 2B4: 69.2%; PD-1: 25.7%) and terminal effectors TEMRA (2B4 69.8% and PD-1 11.0%), while CTLA-4 expression was more equally distributed in all differentiation stages, and TIM-3, KLRG1 and LAG-3 were barely detectable.