Immunochemistry of Lipid A

Abstract

We previously suggested (1, 2, 8–10) that lipid A epitopes are composed of the backbone and acyl groups of the lipid A molecule, and that lipid A has specific and common or cross-reactive epitopes, in which the specificities are derived from the chemical and conformational structures of the backbone and/or acyl groups. In these studies, the in vitro antigenic reactivity of a number of chemically synthesized lipid A analogs with free lipid A preparations from many strains including E. coli, Salmonella minnesota, Klebsiella pneumoniae, Chromobacterium violaceum, Plesiamonas shigelloides and Pseudomonas diminuta was analyzed by enzyme-linked immunosorbent assay (ELISA) and ELISA inhibition test with monoclonal and conventional antibodies against the free lipid A from S. minnesota R595. During these studies, we found that the development of monoclonal antibodies against lipid A having different backbone and/or hydrophobic structures, and the evaluation of antibody-specificity by various assay systems was important to confirm our hypothesis concerninglipid A epitopes.In the presentstudy, therefore, we examined the in vitro antigenic reactivity of synthetic lipid A analogs and bacterial lipid A with monoclonal and conventional antibodies against the lipid A of E. coli F515, E. coli J5 and P. diminuta JCM 2788, as well as S. minnesota R595 by the ELISA, ELISA inhibition test, and the immunodot assay.