Identification and characterization of anti-conjugated azelaic acid antibodies in multiple sclerosis

Human sera from patients with multiple sclerosis (MS) were tested using an enzyme-linked immunosorbent assay (ELISA) method on well plates coated with various dicarboxylic acid (C4 to C10) protein conjugates. Specific immunological binding was found with an azelaic acid (AzeA, C9) conjugate. The antibody titer was higher in the sera from the patients in acute relapse than with the progressive form, and higher than that from sera of patients with other neurological diseases and healthy subjects. Modifications of coating concentrations and of antibody dilutions, and experiments with preadsorption enabled determination of binding specificity. Competition experiments with related conjugates demonstrated that the AzeA residue was 167 times better recognized by antibodies from MS patients in acute relapse than those from controls. The suberic and sebasic acid conjugates which only differ from the AzeA conjugate by one methylene group were less well-recognized by MS sera (11 and 47 times, respectively) than the conjugate AzeA-BSA.