CD28 and Huntington disease: Our study, which is one of the first to characterize T cell subpopulations, showed that age-adjusted percentage of CD38+ naïve CD4+ T cells (CD38+CD45RA+CCR7+CD4+ T cells), naïve CD4+ T cells (CD28+CD45RA+CCR7+CD4+ T cells), and senescence central memory CD8+ T cells (CD57+CD45RA-CCR7+CD8+ T cells) were higher in patients treated with HDF compared to those patients treated with HD.