PMNs from PGRP-S^-/- mice have normal uptake of B subtilis and M luteus but are defective in elimination of ingested bacteria. (A) Peritoneal exudate cells from PGRP-S^+/+ or PGRP-S^-/- mice were incubated in vitro with B subtilis or M luteus, and the numbers of bacteria ingested by PMNs (phagocytic index) were determined at 10 and 20 minutes. The results are means of 4 experiments, and the significance of differences was calculated using the Mann-Whitney U test. (B) Representative photographs of PMNs from PGRP-S^+/+ or PGRP-S^-/- mice after 10 and 20 minutes of phagocytosis of B subtilis (magnification, 10 × 100; Diff-Quik stain). The arrows point to poorly stained bacterial ghosts (partially digested bacteria), often seen in PMNs from PGRP-S^+/+, but not PGRP-S^-/-, mice after 20 minutes of phagocytosis.