THE ANTIBODY REACTIVITY OF MONOCLONAL LIPID-A ANTIBODIES IS INFLUENCED BY THE ACYLATION PATTERN OF LIPID-A AND THE ASSAY SYSTEM EMPLOYED

The influence of the acylation pattern of lipid A on the reactivity of murine monoclonal antibodies (mAb) was tested in different assay syst ems with synthetic lipid A antigens. Both the number and type of fatty acids had an impact on the antigen amounts needed for optimal sensiti zation of sheep red blood cells, on the inhibition capacity of compoun ds and on the reactive antigen amounts in enzyme immunoassay and dot b lot assay. Results obtained with two pentaacyl isomers indicated that the location of fatty acids is of no importance. Although all mAbs use d recognized epitopes residing in the hydrophilic backbone of lipid A, their reactivities were greatly influenced by the number as well as t he type of acyl chains present. In the various assays, the mAbs reacte d either similarly or discrepantly suggesting that epitopes are expose d differently in the test systems. We conclude that for the determinat ion of the reactivity of lipid A mAbs it is useful and sometimes neces sary to run various assays in parallel and to compare mAbs on the basi s of reaction patterns.