Figure 4.

Effect of loss of function mutations in S. pneumoniae on ability to induce apoptosis and inhibit PtdCho synthesis. Microglia were exposed for 4 h to 10⁷ CFU/ml of each bacterial mutant indicated or to 1 μg purified pneumolysin or 1 mM hydrogen peroxide. [methyl-³H]choline incorporation was quantitated by scintillation counting. Values are mean ± SE of six experiments and were compared with mean of control, untreated cells (50,764 cpm/mg protein = 100%). Apoptosis was determined as described in Fig 2 A. *, P < 0.05.