Plays a role in the innate immune response (PubMed:2402637). Binds to the lipid A moiety of bacterial lipopolysaccharides (LPS), a glycolipid present in the outer membrane of all Gram-negative bacteria (PubMed:2427635). Acts as an affinity enhancer for CD14, facilitating its association with LPS (By similarity). Promotes the release of cytokines in response to bacterial lipopolysaccharide (PubMed:2402637). When bound to LPS, interacts (via C-terminus) with soluble and membrane-bound CD14. Detected in blood plasma (at protein level). Belongs to the BPI/LBP/Plunc superfamily. BPI/LBP family.