IMMUNOLOGICAL DETECTION AND MEASUREMENT OF HYPOCHLORITE-MODIFIED LDL WITH SPECIFIC MONOCLONAL-ANTIBODIES

Oxidation of LDL is thought to contribute to the early stages of ather ogenesis. Because myeloperoxidase is present in atherosclerotic lesion s and can produce the strong oxidant hypochlorous acid (HOCl), which c onverts LDL into its high-uptake atherogenic form in vitro, we raised polyclonal and monoclonal antibodies (MoAbs) against HOCl-modified LDL (HOCl-LDL). Characterization of the polyclonal anti-human HOCl-LDL Ab s showed that they cross-reacted strongly with 4-hydroxynonenal-, malo ndialdehyde-, and Cu2+-oxidized LDL. Similarly, polyclonal and some mo noclonal Abs against aldehyde- and Cu2+-modified LDL cross-reacted wit h HOCl-LDL. In contrast to the polyclonal Abs, two selected hybridoma cell line supernatants containing MoAbs raised against HOCl-LDL (MoAb- A and MoAb-B) did not cross-react with either native LDL or aldehyde- or Cu2+-modified LDL. MoAb-A (clone 1B10A11, subtype IgG1 kappa) recog nized an epitope that appeared to be specific for HOCl-LDL and depende d on the tertiary structure of the (lipo)protein, as judged by a lack of cross-reactivity with HOCl-modified human and bovine serum albumin and a loss of reactivity associated with lipoprotein denaturation. MoA b-B (clone 2D10G9, subtype IgC2b kappa), on the other hand, gave ident ical titration curves with HOCL-LDL and HOCl-modified albumins, sugges ting that this antibody recognized epitopes that are commonly generate d on proteins that have been oxidized with HOCl. Thus, MoAb-A and MoAb -B may be useful tools for the investigation of a possible role for HO Cl-mediated damage to (lipo)proteins in atherosclerosis and other infl ammatory diseases.