The LPS binding protein (LBP) is an acute phase protein and an integral component of innate immunity. In normal plasma, LBP was shown to be involved in the response of monocytes to LPS. LBP was also shown to play a detrimental role in models of endotoxemia in mice. Levels of LBP increase during infection. To determine whether the presence of an intact bacterial flora is a prerequisite for normal LBP function, we analyzed the serum concentrations and functional activity of LBP in conventional and germfree mice. Baseline LBP levels were similar in both types of mice, as was the production of the pro-inflammatory cytokines TNFα and IL-6 in whole blood stimulated with LPS. Moreover, D-galactosamine sensitized germfree and conventional mice exhibited similar susceptibility to LPS. We thus conclude that the presence of a bacterial flora is not required to support normal levels and function of LBP.
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