Similar induction of cytokines in PGRP-S^-/- and PGRP-S^-/- mice byB subtilis. Mice were injected intraperitoneally with 2 × 10⁹ (A-B) or the indicated doses (C-D) of B subtilis, and the concentrations of TNF-α and IL-6 in their serum were assayed before (0 hour) and 1.5, 3, or 6 hours (A-B) or 3 hours (C-D) after the bacterial challenge. The results are geometric means ± SE of 8 mice per group. IL-6 at time or dose 0 was undetectable in any of the mice and is shown at the level of detection of the assay. There were no statistically significant differences between PGRP-S^-/- and PGRP-S^+/+ mice, calculated by Mann-Whitney U test.