Molecular structure of human GM-CSF in complex with a disease-associated anti-human GM-CSF autoantibody and its potential biological implications
Michaela Blech, Daniel Seeliger, Barbara Kistler, Margit M. T. Bauer, Mathias Hafner, Stefan Hörer, Markus Zeeb, Herbert Nar, John E. Park
2012 vol: 447 (2) pp: 205-215 doi: 10.1042/BJ20120884
Polyclonal autoantibodies against human GM-CSF (granulocyte/macrophage colony-stimulating factor) are a hallmark of PAP (pulmonary alveolar proteinosis) and several other reported autoimmune diseases. MB007 is a high-affinity anti-(human GM-CSF) autoantibody isolated from a patient suffering from PAP which shows only modest neutralization of GM-CSF bioactivity. We describe the first crystal structure of a cytokine-directed human IgG1λ autoantibody-binding fragment (Fab) at 1.9 Å (1 Å=0.1 nm) resolution. Its CDR3-H substantially differs from all VH7 germline IgG1 structures reported previously. We derive a reliable model of the antigen-autoantibody complex by using NMR chemical shift perturbation data in combination with computational methods. Superposition of the modelled complex structure with the human GM-CSF-GM-CSF ternary receptor complex reveals only little overlap between receptor and Fab when bound to GM-CSF. Our model provides a structural basis for understanding the mode of action of the MB007 autoantibody.
Topics: Two-dimensional; CDR, Complementarity-determining region, GM-CSF, Granulocyte/macrophage colony-stimulating factor, GM-CSFR, GM-CSF receptor, hGM-CSF, human GM-CSF, LED, Light-emitting diode; MD, Molecular dynamics, Monolith – MicroScale Thermophoresis, MST, Proteins, Publications