Restricted V gene usage and VH/VL pairing of mouse humoral response against the N terminal immunodominant epitope of the amyloid β peptide

Over the last decade the potential of antibodies as therapeutic strategies to treat Alzheimer s disease (AD) has been growing based on successful experimental and clinical trials in transgenic mice Despite undesirable side effects in humans using an active immunization approach immunotherapy still remains one of the most promising treatments for AD In this study we analyzed the V genes of twelve independently Isolated monoclonal antibodies raised against the N-terminal immunodominant epitope of the amyloid 3 peptide (A beta or A beta) Surprisingly we found a high and unusual level of restriction in the VH/VL pairing of these antibodies Moreover these antibodies mostly differ in their heavy chain complementary determining region 3 (HCDR3) and the residues in the antibodies which contact A beta are already present in the germline V-genes Based on these observations and or co-crystal structures of antibodies with A beta the aim of the current study was to better understand the role of antibody V-dorncims HCDR3 regions key contact residue (H58) and germline encoded residues in A beta recognition For that purpose we designed and produced a range of recombinant Fab constructs All the Fabs were tested and compared by surface plasmon resonance on A beta(1-16) A beta(1-42) high molecular weight and A beta(1-42) low molecular weight soluble oligomers Although all the Fabs recognized the A beta(1-16) peptide and the A beta(1-42) high molecular weight soluble oligomers they did not bind the A beta(1-42) low molecular weight soluble oligomers Furthermore we demonstrated that (1) an aromatic residue at position H58 in the antibody is essential in the recognition of A beta and (2) Fabs based on germline V-genes bind to A beta monomers with a low affinity These findings may have Important implications in designing more effective therapeutic antibodies against A beta (C) 2010 Elsevier Ltd All rights reserved