TALF PEPTIDE-IMMUNOGLOBULIN-G CONJUGATES THAT BIND LIPOPOLYSACCHARIDE

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., Cavaillo n J-M., Wainwright N., Warren H.S. Synthetic peptides that mimic the b inding 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)propionat e (SPDP). The resulting peptide-IgG conjugates contained 4-8 moles pep tide per mole IgG and were evaluated for the ability to bind and neutr alize LPS. Both conjugates bound LPS in a LPS capture Western blot ass ay. In a fluid-phase radioimmunoassay, half-maximal binding of 5 mu g/ ml LPS by many different Escherichia coli strains occurred at 50-100 m u g/ml for both conjugates. Coagulation of Limulus amoebocyte lysate w as only minimally inhibited by 5 mu g/ml of each conjugate. Our data s uggest that TALF peptide-IgG conjugates bind LPS with high affinity, b ut only weakly neutralize LPS. These studies provide an initial step t owards the development of peptide-IgG preparations that might be usefu l for the treatment of Gram-negative sepsis by binding and clearing LP S.