Table 1

Classification of PAP

Primary PAP: GM-CSF signalling disruption
  • Autoimmune PAP (GM-CSF autoantibodies)

    Hereditary PAP (mutations in genes encoding GM-CSF receptor)

Secondary PAP: reduction in function and/or number of alveolar macrophages
  • Haematological disorders


    Immune deficiency syndromes

    Chronic inflammatory syndromes

    Chronic infections

    Toxic inhalation syndromes


Congenital PAP: impaired surfactant production
  • Mutations in surfactant proteins (SFTPA, SFTPB, SFTPC)

    Mutations in lipid transporter (ABCA3)

    Mutations affecting lung development (TTF1)

GM-CSF: granulocyte–macrophage colony-stimulating factor.