Flow cytometric analysis of apoptosis using the APO-BRDU kit. Cells were incubated with Br-dUTP in the presence of TdT enzyme to incorporate Br-dUTP into exposed 3′-OH ends. Quantitation of Br-dUTP sites was determined by flow cytometric analysis using fluorescein-conjugated anti-BrdU monoclonal antibody. Positive (apoptotic) and negative (nonapoptotic) control HL60 cells, treated with camptothecin or untreated, were provided by the company. (A) Negative control (—); positive control (· · ·). (B) EBV-positive X50-7 cells treated with LMP-1 antisense oligodeoxynucleotide (· · ·); treated with control SS1 oligodeoxynucleotide (—); or untreated (). (C) EBV-negative Louckes line treated with LMP-1 antisense oligodeoxynucleotide (· · ·); treated with control SS1 oligodeoxynucleotide (—); or untreated ().