Generation and testing of an anti-idiotype that acts as a surrogate antigen for oxidized LDL (OxLDL) in serological studies measuring anti-OxLDL antibodies
Author(s)
Chang, Shang-Hung
Type
Thesis
Abstract
Atherosclerosis is thought to be mediated by immune response in which oxidized low
density lipoprotein (OxLDL) is one of the major antigens. The exact linkage between
anti-OxLDL antibodies and atherosclerosis, however, is controversial. One of the
sources of this controversy is the inherently heterogeneous and complex nature of
OxLDL as an antigen. This study aims to identify and characterise a new type of
structurally definable surrogate antigen for OxLDL for use in serologic assays.
The study applied two techniques for cloning antibodies. The first step was the
generation of a monoclonal anti-OxLDL antibody, designated LO-1, by fusing mouse
B cells and myeloma cells. The mouse used in this fusion was not immunized but fed
with high fat diet to reflect the physiologic but hyperlipidemic immune environment.
The second step was to use a phage display system (Tomlinson library of single chain
variable antibody fragments) to screen anti-idiotypic antibodies (anti-id) against an
anti-OxLDL monoclonal antibody generated from that mouse. The anti-id selected for
further characterisation, was designated H3. This anti-id, which probably mimics
both peptide and lipid components of OxLDL, was used as an antigen in a serologic
assay (both in mice and humans) and compared with ordinary OxLDL antigens
conventionally used by earlier researchers. Titres of antibodies against H3 correlated
well with antibodies against malondialdehyde-conjugated LDL. Although the overall
performance of anti-H3 antibodies was no better than conventional anti-OxLDL assays in predicting atherosclerosis, they showed an inverse relationship with the
extent of left anterior descending coronary artery stenosis in patients with established
coronary artery disease.
This project has developed a novel approach to measuring OxLDL antibodies. The
proposed unique mimicry of both the lipoprotein and the phospholipid components of
OxLDL may reveal a functionally significant epitope of OxLDL that has not been
successfully mapped by previously reported methodologies. The novel anti-id H3 and
the corresponding mimetic region of OxLDL therefore provide new insight and new
tools for future research on the humoral response related to atherosclerosis.
density lipoprotein (OxLDL) is one of the major antigens. The exact linkage between
anti-OxLDL antibodies and atherosclerosis, however, is controversial. One of the
sources of this controversy is the inherently heterogeneous and complex nature of
OxLDL as an antigen. This study aims to identify and characterise a new type of
structurally definable surrogate antigen for OxLDL for use in serologic assays.
The study applied two techniques for cloning antibodies. The first step was the
generation of a monoclonal anti-OxLDL antibody, designated LO-1, by fusing mouse
B cells and myeloma cells. The mouse used in this fusion was not immunized but fed
with high fat diet to reflect the physiologic but hyperlipidemic immune environment.
The second step was to use a phage display system (Tomlinson library of single chain
variable antibody fragments) to screen anti-idiotypic antibodies (anti-id) against an
anti-OxLDL monoclonal antibody generated from that mouse. The anti-id selected for
further characterisation, was designated H3. This anti-id, which probably mimics
both peptide and lipid components of OxLDL, was used as an antigen in a serologic
assay (both in mice and humans) and compared with ordinary OxLDL antigens
conventionally used by earlier researchers. Titres of antibodies against H3 correlated
well with antibodies against malondialdehyde-conjugated LDL. Although the overall
performance of anti-H3 antibodies was no better than conventional anti-OxLDL assays in predicting atherosclerosis, they showed an inverse relationship with the
extent of left anterior descending coronary artery stenosis in patients with established
coronary artery disease.
This project has developed a novel approach to measuring OxLDL antibodies. The
proposed unique mimicry of both the lipoprotein and the phospholipid components of
OxLDL may reveal a functionally significant epitope of OxLDL that has not been
successfully mapped by previously reported methodologies. The novel anti-id H3 and
the corresponding mimetic region of OxLDL therefore provide new insight and new
tools for future research on the humoral response related to atherosclerosis.
Date Issued
2010-02
Date Awarded
2010-08
Copyright Statement
Attribution NoDerivatives 4.0 International Licence (CC BY-ND)
Advisor
haskard, Dorian
Sponsor
Changgeng ji nian yi yuan
Publisher Department
National Heart and Lung Institute
Publisher Institution
Imperial College London
Qualification Level
Doctoral
Qualification Name
Doctor of Philosophy (PhD)