Recombinant human soluble MD-2 binds to E coli but has no bactericidal effect. (A) Soluble MD-2 binding to E coli and B subtilis. Wild-type heat-killed E coli (left) and B subtilis (right) were incubated with increasing concentrations of His-tagged recombinant human sMD-2. Soluble MD-2 binding to bacteria was measured by FACS using an APC-conjugated monoclonal anti-polyHis antibody detecting MD-2 bound to bacteria. A negative control was an irrelevant His-tagged protein (murine IL-6). This is one experiment representative of 3 similar experiments; n.d. indicates not done. (B) Soluble MD-2 does not influence the growth of E coli. E coli K12 were cultured in the presence or absence of 10 μg/mL recombinant human soluble MD-2. Bacterial growth was determined using OD600 absorbance of the culture medium. This experiment was repeated twice with the same results.
