FIG 4.

Effect of NK cell depletion on primary and secondary C. muridarum infection in CD4-depleted and nondepleted C57BL/6 mice. (A) Primary infection course in NK cell-depleted (anti-NK1.1) and nondepleted C57BL/6 mice. The vertical dashed line at day 38 represents the final anti-CD4 injection. (B) Secondary infection course in nondepleted C57BL/6 mice or in mice depleted of NK cells or NK cells and CD4⁺ T cells. The vertical dashed line at day 26 represents the final anti-CD4 and anti-NK1.1 injections. Experiments with CD4-depleted C57BL/6 mice from Fig. 3 ran concurrently with NK cell studies for Fig. 4 and thus are displayed again (green bars) for statistical comparison. There were no statistical differences between C57BL/6 and anti-NK1.1 mice during primary infection. *, P < 0.05; ***, P < 0.001; ****, P < 0.0001 (n = 5 mice for all experimental groups).