APPEARANCE OF CROSS-LINKED PROTEINS IN HUMAN ATHEROMA AND RAT PRE-FIBROTIC LIVER DETECTED BY A NEW MONOCLONAL-ANTIBODY

A new monoclonal antibody against malondialdehyde (MDA)-treated low de nsity lipoprotein (LDL) was raised using homogenate of human atheroma as immunogen. This antibody, DLH2, was obtained by selecting the clone s which did not react to native LDL but did react to copper-induced ox idized LDL (OxLDL). DLH2 showed a greater activity to MDA-LDL than to OxLDL. When LDL was treated with various aldehyde containing reagents, treatment of LDL with glutaraldehyde or MDA greatly increased the rea ctivity to the antibody, while LDL treated with 2,4-hexadienal or 4-hy droxynonenal was not reactive. Among many proteins tested, high densit y lipoprotein, bovine serum albumin and hemoglobin showed significant activity to DLH2 after they were treated with MDA or glutaraldehyde. W hen low density and high density lipoproteins treated with MDA were su bjected to immunoblot analysis, newly formed products larger than the original apolipoproteins were detected with the antibody, suggesting t hat this antibody recognizes aggregated proteins with divalent short c hain cross linkers. The antigenic materials were shown by immunohistoc hemical analysis to be present in foamy macrophages in human atheromat ous lesions. DLH2 antigen did not colocalize either with apolipoprotei n B. Furthermore, we found a massive accumulation of the antigenic mat erial in Kupffer cells in the liver of rats treated with alcohol and c arbonyl iron, a model of hepatic fibrosis due to oxidative stress. The se results suggest the presence of cross linked proteins in damaged ti ssues. (C) 1998 Elsevier Science B.V.