Neutralization and clearance of GM-CSF by autoantibodies in pulmonary alveolar proteinosis

Luca Piccoli, Ilaria Campo, Chiara Silacci Fregni, Blanca Maria Fernandez Rodriguez, Andrea Minola, Federica Sallusto, Maurizio Luisetti, Davide Corti, Antonio Lanzavecchia

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Abstract

Pulmonary alveolar proteinosis (PAP) is a severe autoimmune disease caused by autoantibodies that neutralize GM-CSF resulting in impaired function of alveolar macrophages. In this study, we characterize 21 GM-CSF autoantibodies from PAP patients and find that somatic mutations critically determine their specificity for the self-antigen. Individual antibodies only partially neutralize GM-CSF activity using an in vitro bioassay, depending on the experimental conditions, while, when injected in mice together with human GM-CSF, they lead to the accumulation of a large pool of circulating GM-CSF that remains partially bioavailable. In contrast, a combination of three non-cross-competing antibodies completely neutralizes GM-CSF activity in vitro by sequestering the cytokine in high-molecular-weight complexes, and in vivo promotes the rapid degradation of GM-CSF-containing immune complexes in an Fc-dependent manner. Taken together, these findings provide a plausible explanation for the severe phenotype of PAP patients and for the safety of treatments based on single anti-GM-CSF monoclonal antibodies.

Original languageEnglish
Article number7375
JournalNature Communications
Volume6
DOIs
Publication statusPublished - Jun 16 2015

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ASJC Scopus subject areas

  • Biochemistry, Genetics and Molecular Biology(all)
  • Chemistry(all)
  • Physics and Astronomy(all)

Cite this

Piccoli, L., Campo, I., Fregni, C. S., Rodriguez, B. M. F., Minola, A., Sallusto, F., Luisetti, M., Corti, D., & Lanzavecchia, A. (2015). Neutralization and clearance of GM-CSF by autoantibodies in pulmonary alveolar proteinosis. Nature Communications, 6, [7375]. https://doi.org/10.1038/ncomms8375