Nylon wool purified splenic T cells were cultured in 24 wells at 106 cells/ml at 37°C in 5% CO2.. At indicated times of culture (0h, 6h, 12h), cells were washed twice, and were stained with Annexin V FITC. Significantly increased rate of apoptosis was observed in susceptible C57BL/6 mice than in resistant CBA/J mice in the acute stage of T. gondii infection (6 days postinfection) (p<0.001). This was evident in ex vivo T cells, and the difference was maintained in T cells cultured for extended periods of time (6 hr, 12 hr). The level of apoptosis in susceptible C57BL/6 mice was significantly higher in the acute stage (6 days postinfection) than in the early stage (3 days postinfection) of infection (p<0.001). Similar pattern was seen when the rate of apoptosis was measured by the subG0 DNA assay. Cells with less FL2 fluorescence than the 2N DNA peak were considered having subG0 DNA. Significantly augmented DNA degradation was observed in the susceptible C57BL/6 mice than in resistant CBA/J mice (p<0.001). Data (mean ± SD) are representative of three independent experiments with three mice per group.
