FITC-LPSs from E. coli serotypes O111:B4 (A) and O55:B5 (B) were preincubated, at 1.25 and 2.5 μg/ml, respectively, with three different concentrations of proteins and peptides (10, 1 and 0.25 μg/ml) in PBS-EDTA with 0.1% BSA and added to wells containing biotinylated polymyxin B captured by deglycosylated avidin. Results are expressed as percentage inhibition of LPS binding to captured polymyxin B by the target protein/peptide, and are the mean values ±SD for duplicate wells. The average optical densities (492 nm) of control wells (without inhibitor) were 0.904 (±0.042, red dashed line) and 0.842 (±0.036, red dashed line) for serotypes O111:B4 and O55:B5, respectively. Differences were considered significant at p <0.05. NS: not significant. HB, hemoglobin; HF1, histone f1 fraction; LF, lactoferrin; LSZ, lysozyme; MEL, melittin; MF6p, synthetic FhHDM-1/MF6p; MYO, myoglobin; P3L, A. simplex peptide: MCQCVQKYGTEFCKKRLA; PMX, polymyxin B.