THE SERUM CONCENTRATION OF THE ADVANCED GLYCATION END-PRODUCT N-EPSILON-(CARBOXYMETHYL)LYSINE IS INCREASED IN UREMIA

Advanced glycation end pro ducts (AG Es) such as pentosidine and N-eps ilon-(carboxymethyl)lysine (CML) have been traditionally quantified by HPLC or gas chromatography-mass spectrometry (GC/MS). Enzyme-linked i mmunosorbent assays (ELISA) have been introduced as a convenient alter native to simplify the detection and measurement of AGEs in proteins a nd tissues, but some of these studies are limited by the lack of infor mation on the structure of the epitopes recognized by antibodies to AG E-proteins. In this work we demonstrate that an antibody used in a pre vious study, reporting increased levels of AGEs in patients with diabe tes or on continuous ambulatory peritoneal dialysis (CAPD) and hemodia lysis (HD), recognizes CML as its major epitope. We also show that the re is a significant correlation between the concentration of AGEs in s erum measured by ELISA and a GC/MS assay for CML in serum proteins. Bo th analyses yielded comparable results, with patients on CAPD and I-ID having about threefold higher AGE-or CML-concentrations in their seru m. Our data suggest that ELISA assays for CML should be useful for the clinical measurement of AGEs in serum proteins.