Antigenic determinants of lipid A analyzed with synthetic models and monoclonal antibodies.

Three monoclonal antibodies directed against the hydrophobic region (lipid A backbone) of Bordetella pertussis endotoxin were used to analyze cross reactivities of lipid A and synthetic glycolipids structurally related to it. Reactivity of mAb with synthetic compounds was measured by a radioimmunoassay inhibition test. Our data indicate that 3-acyloxyacyl groups do not play a significant role, and suggest that a phosphate and a hydroxyl group, at two carbon distance from each other, are part of a single antigenic determinant recognized by the monoclonal antibodies.