CD28 and stroke disorder: Within 24 hours of onset, the stroke patients showed an increased frequency of CD4+CD28– T cells (14.1 ± 4.4%) as well as elevated expression of CD137 (Figure1) on CD4+ (4.9 ± 3.2%) and CD4+CD28– T cells (2.6 ± 2.1%) compared with the ACS and NC groups (CD4+CD28–: 9.0 ± 4.6% and 8.1 ± 3.3%, P = 0.0004 and P < 0.0001; CD137 expression on CD4+ T cells: 2.2 ± 1.7% and 1.3 ± 1.0%, P = 0.0018 and P < 0.0001; CD137 expression on CD4+CD28– T cells: 0.7 ± 0.7% and 0.5 ± 0.3%, P = 0.0004 and P < 0.0001), but no significant differences were found between the ACS group and the NC group (Table2).