Daintain,a macrophage inflammatory factor,was characterized.To investigate the regulatory mechanism of daintain on pancreatic βcells,daintain was coupled to CNBr -Sepharose 4B,and the binding protein of daintain in pancreas was isolated by affinity chromatography,then it was characterized as cyatathionine-beta-synthase (CBS) in the database of mascot according to the peptide mass fingerprint and amino acid sequence of two peptide fragments with trpsin digestion.The interaction of daintain with CBS suggests that daintain may regulate the activity of CBS,resulting in the accumulation of homocysteine.