Human PGRP-S shows synergistic antibacterial effect with lysozyme against E coli K12. (A) Lysis of lysozyme-treated E coli cells. Lysozyme-treated E coli cells (⋄) were incubated in 10 mM NaPB, pH 7.4, with rhPGRP-S (4 μg/mL, [▴]; 8 μg/mL, [•]) or PMBN (2.5 μg/mL, [▦]), and the change in OD at 600 nm was monitored for 10 minutes. Data represent the mean ± SD of 3 independent experiments. (B) Growth inhibition of E coli cells. E coli cells were incubated in 1 × TSB (3% wt/vol) with 50 μg/mL lysozyme (▦), 25 μg/mL rhPGRP-S (▴), 8 μg/mL rhPGRP-S and 50 μg/mL of lysozyme (•), or no protein (⋄). Tubes were shaken at 300 rpm for 5 hours, and bacterial density was monitored by measurement of optic density (OD) at 600 nm at 1-hour intervals. Data represent the mean of duplicate samples from 1 of 2 similar experiments.