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 systems with synthetic lipid A antigens. Both the number and type of fatty acids had an impact on the antigen amounts needed for optimal sensitization of sheep red blood cells, on the inhibition capacity of compounds and on the reactive antigen amounts in enzyme immunoassay and dot blot assay. Results obtained with two pentaacyl isomers indicated that the location of fatty acids is of no importance. Although all mAbs used recognized epitopes residing in the hydrophilic backbone of lipid A, their reactivities were greatly influenced by the number as well as the type of acyl chains present. In the various assays, the mAbs reacted either similarly or discrepantly suggesting that epitopes are exposed differently in the test systems. We conclude that for the determination of the reactivity of lipid A mAbs it is useful and sometimes necessary to run various assays in parallel and to compare mAbs on the basis of reaction patterns.