FIG 7.

NMII does not induce death in caspase-1-deficient B1a B cells. B1a B cells were harvested and purified from either wild-type or caspase-1-deficient mice and infected with NMII. (A) Staining by TUNEL was used to visualize DNA fragmentation following NMII infection. (B) Infected cell numbers were counted at 3 days postinfection. (C) The MTS assay was used to measure the numbers of viable cells among caspase-1-knockout (KO) or wild-type B1a B cells infected with NMII at day 3 postinfection. **, P < 0.01. These data indicate that caspase-1 is required for B1a cell death induction and that caspase-1-deficient cells are more permissive to infection with NMII.