Monoclonal antibody EMR1a/212D recognizing site of deposition of extracellular lipid in atherosclerosis: purification and characterization of the antigen

Abstract

The monoclonal antibody EMR1a/212D, which recognizes the extracellular matrix in which lipids are deposited in atherosclerotic lesions, was developed previously. The macromolecule containing the epitope recognized by this antibody was purified from serum of WHHL rabbits, antigenic material similar to that found in serum and atherosclerotic plaques. The antigenic material was not associated with lipoproteins in serum. The antigenic material was purified in a single band by SDS-PAGE followed by DEAE-Sepharose CL-6B column chromatography (Pharmacia, Uppsala, Sweden), EMR1a/212D coupled immunoaffinity column chromatography, and HPLC equipped with a TSK gel G3000SWXL (Toso, Japan) column. The purified antigenic material was a glycoprotein of molecular weight 66 kd. It was remarkably high in glutamic acid and aspartic acid but low in arginine and lysine. It had an isoelectric point of pH from 5.4 to 5.9. It contained 22.2 mg of sugar per 100 mg protein, and sialic acid at least expressed the activity of the epitope because the antigenic activity was decreased by neuraminidase treatment.