Major constituents of lung defences

Airways and their mucosa
    Luminal defence mechanisms
        Anatomical barrier
        Mucociliary clearance
        Secretory IgA
        Lysozymes, lactoferrins
    Epithelial cells
        Epithelial barrier
        Mucin release
        Antimicrobial peptides
        Bacterial receptors
        Chemotactic factors
        Growth factors; cytokines
    Blood derived cells of the mucosa
        Dendritic cells
        Lymphocytes (T-cells; γδ; NK cells)
        B lymphocytes
        Eosinophils; mast cells; basophils
Alveolar spaces
    Pneumocyte types I and II
    Alveolar macrophages
    IgG and opsonins
  • Ig: immunoglobulin; NK: natural killer.