TALF peptide-immunoglobulin G conjugates that bind lipopolysaccharide

Abstract

Several peptides mimicking the amino acid sequence of Tachypleus anti-LPS factor (TALF) bind LPS with high affinity and some neutralize LPS in vitro and in vivo (Kloczewiak M., Black K.M., Loiselle P., Cavaillon J-M., Wainwright N., Warren H.S. Synthetic peptides that mimic the binding site of horseshoe crab anti-lipopolysaccharide factor. J Infect Dis 1994; 170: 1490-1497). Two such peptides, TALF29-59 and TALF41-53, were covalently coupled to human IgG via a disulfide bond using the heterobifunctional linker, N-succinimidyl-3-(2-pyridyldithio)propionate (SPDP). The resulting peptide-lgG conjugates contained 4-8 moles peptide per mole IgG and were evaluated for the ability to bind and neutralize LPS. Both conjugates bound LPS in a LPS capture Western blot assay. In a fluid-phase radioimmunoassay, half-maximal binding of 5 μg/ml LPS by many different Escherichia coli strains occurred at 50-100 μg/ml for both conjugates. Coagulation of Limulus amoebocyte lysate was only minimally inhibited by 5 μg/ml of each conjugate. Our data suggest that TALF peptide-lgG conjugates bind LPS with high affinity, but only weakly neutralize LPS. These studies provide an initial step towards the development of peptide-lgG preparations that might be useful for the treatment of Gram-negative sepsis by binding and clearing LPS.