CASP3 and Huntington disease: When PBMCs from HD were exposed to blocking anti-CD5 Abs (αCD5) prior to TCR stimulation, we observed (i) increased levels of p-ERK after 5 min (Wilcoxon p=0.007, Figure 5G), (ii) increased CD25 expression after 24 hr (Wilcoxon p=0.03, Figure 5H), and (iii) increased percentages of dying naïve CD8 T cells as assessed by active caspase 3 staining after 24 hr (Wilcoxon p=0.003) (Figure 5—figure supplement 3).