Analysis of cell activation and BrdU incorporation during the early phase of in vitro SAg-mediated deletion of Vβ8.1 DP TG thymocytes. Dot plots show the CD4 versus CD8 profiles of TCR Vβ8.1 TG thymocytes cultured for 24 hours alone or with BALB.D2 splenic B cells. The absolute cell number of DP and SP thymocytes is indicated. Histograms represent the CD69 expression and BrdU incorporation of DP thymocytes. The percentage of CD69⁺ (FL2 > 20) and BrdU⁺ (FL1 > 80) DP thymocytes are indicated. The experiment is representative of three experiments with similar results.