Apoptosis among CD3⁺ T cells.

PBMCs were obtained from a patient 21 days following transplantation, cultured for 24 hours, and stained with PE-labeled anti-CD3 mAb (panels A, C, and E) or with PE-labeled anti-CD3 mAb and FITC-labeled IgG₁ isotype control antibody (panels B, D, and F) followed by 7AAD. Less than 1% of the T cells were stained with FITC-labeled IgG₁ isotype control antibody. T-cell apoptosis was measured by using FSC and the intensity of 7AAD fluorescence (panel E or F) of cells noted in the R1 gate (panel A or B) and R2 gate (panel C or D).