Characteristics of purified T cells. The frequency of CD8+ and CD4+ T cells before (top) and after (bottom) separation using AutoMacs are presented. Effector CTLs were labeled with magnetic CD8a (Lyt-2) MicroBeads and CD8+ and CD8- cells collected by passage through a magnetized column. The cells were stained with CD8-PE and CD4-FITC conjugated monoclonal antibodies, respectively. Forward (FS) and side scatter (SC) plots of total lymphocytes (left), two-parameter histogram of gated CD8-PE+/CD4-FITC+ cells (middle) and prism display of cell frequencies are shown for un-separated CTL (top) and purified CD8+ CTLs (bottom) are shown a representative sample.