CD4 and Huntington disease: T-cell proliferation was fully abrogated in the LPDS condition in HD and CLL CD4+ (Fig. 1A) and CD8+ T cells (Supplementary Fig. 1B), indicating a clear dependency on exogenous cholesterol for proliferation, which was evident in the percentage of dividing cells and in the average number of cell divisions that a cell in the original population has undergone (division index).