REACTIVITY OF MURINE AND HUMAN RECOMBINANT LPS-BINDING PROTEIN (LBP) WITH LPS AND GRAM-NEGATIVE BACTERIA

The serum lipopolysaccharide (LPS) binding protein, LBP, has been show n to greatly enhance cellular responses to low concentrations of LPS. Purified LBP facilitates the transfer of LPS to membrane-bound or solu ble CD14; the CD14/LPS complex then triggers a signal in responsive ce lls. We have cloned and sequenced a cDNA encoding murine LBP, and prod uced recombinant marine LBP using a baculovirus expression system. Usi ng either a solid-phase or a cytofluorometric assay, recombinant murin e and human LBP were found to bind avidly to free LPS, but only weakly to live bacteria from most LPS-containing Gram negative strains. Bind ing correlated loosely with the length and composition of the polysacc haride O chains. However, recombinant LBP did bind well to all heat-ki lled bacterial preparations. These findings suggest that LBP could be implicated in the response to killed but not live Cram negative bacter ia. (C) 1997 Wiley-Liss, Inc.