Concentrations and ratios of immunoreactive big-endothelin-1 and endothelin-1 in human, rat and rabbit plasma.

We have developed a radioimmunoassay for big-endothelin-1, based on a new antiserum recognizing human big-endothelin(1-38). On a molar base the antibody showed virtually no cross-reactivity with endothelin-1, -2, -3 (less than 0.001%), 14% cross-reactivity with the C-terminal big-endothelin(22-38) and only 0.

A rabbit antiserum raised against the hexapeptide endothelin(16-21) shows different binding affinities for endothelin-1, -2 and -3.

A antiserum raised against the C-terminal hexapeptide ET16-21 common to ET-1, -2 and -3 was produced and characterized with respect to its binding properties for ET-1, -2, -3, ET16-21, the C-terminal octapeptide ET14-21, its derivative Phe21-ET14-21 and human big-ET-1. The antibody reacted with the peptides with decreasing binding affinities in the order: ET-1 greater than ET-2 greater than or equal to ET16-21 = ET 14-21 much greater than Phe21-ET14-21. It showed no crossreactivity with human big-ET-1.

Antibodies to core lipopolysaccharide determinants: absence of cross-reactivity with heterologous lipopolysaccharides.

Using monoclonal antibodies directed against defined epitopes of endotoxin core, this study demonstrated that the presentation of lipopolysaccharide (LPS) to antibodies is critical for measuring the specific binding of antibodies to LPS structures. False cross-reactive reactions apparently were observed when free core LPS or lipid A were used as antigens in ELISA, whereas coating with complexes of high-density lipoproteins with core LPS increased both the sensitivity and the specificity of the test compared with coating with free core LPS, so that nonspecific binding of antibodies was largely avoided. Using this technique, it was not possible to find broadly cross-reactive core LPS antibodies after immunization of rabbits and humans with rough mutants of gram-negative bacteria.