PRF1 and Huntington disease: Interestingly, we found a positive correlation between the production of intracellular perforin, but not granzyme B, in CD8+ HLA-DR+ T cells after culturing PBMCs in the presence of plasma from HD, R or NR patients and the percentage of CD8+ HLA-DR+ T cells found in peripheral blood in R and NR patients (Supplementary Figure S1A,B).