Detection of apoptosis in a heterogenous cell population using flow cytometry

Apoptosis induced in human leukemic cells (promyelocytic human leukemic cells HL-60, multidrug-resistant subline HL-60/VCR) and human ovarian carcinoma cells (A2780 and multidrug-resistant subline A2780/ADR) in vitro was detected by flow cytometric analysis or DNA electrophoresis. The cytofluorometric techniques utilized, i. e. detection of phosphatidylserine exposed at the outer surface of the plasma membrane, identification of cells with "sub-G0" DNA content or increased light side scatter (cell internal structure) correlated with the electrophoretic determination of DNA fragmentation ("DNA ladder"). Detection of the 34 kDa mitochondrial protein recognized by the monoclonal antibody Apo2.7 yielded elevated percentages of apoptotic cells, suggesting that this technique detecting both early and late apoptosis in digitonin-fixed cells might not be restricted to the specific detection of programmed cell death.