AL amyloid imaging and therapy with a monoclonal antibody to a cryptic epitope on amyloid fibrils

• Published in: PloS one Vol. 7; no. 12; p. e52686
• Main Authors: Wall, Jonathan S, Kennel, Stephen J, Williams, Angela, Richey, Tina, Stuckey, Alan, Huang, Ying, Macy, Sallie, Donnell, Robert, Barbour, Robin, Seubert, Peter, Schenk, Dale
• Format: Journal Article
• Language: English
• Published: United States Public Library of Science 26.12.2012; Public Library of Science (PLoS)
• Subjects: Alzheimer's disease; Amino Acid Sequence; Amino acids; Amyloid - chemistry; Amyloid - immunology; Amyloid - metabolism; Amyloidosis; Amyloidosis - diagnostic imaging; Amyloidosis - immunology; Amyloidosis - therapy; Animals; Antibodies, Monoclonal, Murine-Derived - pharmacokinetics; Antibodies, Monoclonal, Murine-Derived - therapeutic use; Antibody Affinity; Antigen-antibody reactions; Antigenic determinants; Autoradiography; Bence Jones Protein - chemistry; Binding, Competitive; Biology; Biopharmaceuticals; Chains; Epitopes; Epitopes - immunology; Fibrils; Humans; Imaging; Immunoglobulins; Immunohistochemistry; Immunotherapy; Kidney - metabolism; Kidney - pathology; Kidney diseases; Leukocytes (neutrophilic); Light; Light chains; Liver - metabolism; Liver - pathology; Localization; Macrophages; Medical prognosis; Medicine; Mice; Mice, SCID; Monoclonal antibodies; Organ Specificity; Organs; Pancreas - metabolism; Pancreas - pathology; Peptide Fragments - immunology; Peptides; Photon emission; Protein A; Protein Binding; Proteins; Radiopharmaceuticals - pharmacokinetics; Regression analysis; Single photon emission computed tomography; Substrates; Surface plasmon resonance; Tissue Distribution; Tomography, Emission-Computed, Single-Photon; Whole Body Imaging; South San Francisco California; California; United States > US; Tennessee
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0052686

The monoclonal antibody 2A4 binds an epitope derived from a cleavage site of serum amyloid protein A (sAA) containing a -Glu-Asp- amino acid pairing. In addition to its reactivity with sAA amyloid deposits, the antibody was also found to bind amyloid fibrils composed of immunoglobulin light chains. The antibody binds to synthetic fibrils and human light chain (AL) amyloid extracts with high affinity even in the presence of soluble light chain proteins. Immunohistochemistry with biotinylated 2A4 demonstrated positive reaction with ALκ and ALλ human amyloid deposits in various organs. Surface plasmon resonance analyses using synthetic AL fibrils as a substrate revealed that 2A4 bound with a K(D) of ∼10 nM. Binding was inhibited in the presence of the -Glu-Asp- containing immunogen peptide. Radiolabeled 2A4 specifically localized with human AL amyloid extracts implanted in mice (amyloidomas) as evidenced by single photon emission (SPECT) imaging. Furthermore, co-localization of the radiolabeled mAb with amyloid was shown in biodistribution and micro-autoradiography studies. Treatment with 2A4 expedited regression of ALκ amyloidomas in mice, likely mediated by the action of macrophages and neutrophils, relative to animals that received a control antibody. These data indicate that the 2A4 mAb might be of interest for potential imaging and immunotherapy in patients with AL amyloidosis.