[The development of radioimmunoassay and studies of removal system for advanced glycosylation endproduct].

Free amino groups of proteins can react with a reducing sugar such as glucose via an Amadori rearrangement. Following Amadori product formation, further reactions and rearrangements of the Amadori products form stable brown pigments (advanced glycosylation endproduct, AGE) which possess characteristic spectra and fluorescent property. This process has been known as the Maillard reaction and some reports indicate that this process may play some role in the pathogenesis of diabetic complications and aging process. Recently, a chromophore, 2-(2-furoyl)-4(5)-(2-furanyl)-1H-imidazole (FFI), as one of AGE, was isolated from acid hydrolysate of bovine serum albumin (BSA) incubated with glucose. In this report, a radioimmunoassay (RIA) for FFI was developed. To investigate the mechanism for removal of AGE-protein in vivo, the interaction of FFI- proteins with mouse peritoneal macrophage was characterized using FFI-BSA as a probe. A derivative of FFI, 4-furanyl-2-furoyl-1H-imidazole-1-hexanoic acid (FFI-HA), was coupled to keyhole limpet hemocyanin (KLH). FFI-HA/KLH was used to immunize guinea pigs. The antiserum exhibited high affinity binding to FFI, but had no cross-reactivity to the structurally related compounds containing an imidazole ring or furan ring(s). The levels of FFI and relative fluorescence in bovine serum albumin incubated with glucose for 0-49 days were measured. A time-dependent increase was obtained in the amount of acid-liberated FFI and a concomitant increase in fluorescence intensity. The RIA described here had satisfactory reproducibility as judged by the intra-assay precision 3.4-6.8% and the inter-assay precision 7.3-8.9%.(ABSTRACT TRUNCATED AT 250 WORDS)