Thorax 56:419-420 doi:10.1136/thorax.56.6.419
  • Editorial

Dendritic cell ontogeny as an aetiological factor in respiratory tract diseases in early life

  1. P G HOLT
  1. Division of Cell Biology
  2. TVW Telethon Institute for Child Health Research
  3. P O Box 855, West Perth
  4. WA 6872, Australia

      Large populations of dendritic cells (DCs) are found throughout the respiratory tract, the most prominent comprising a contiguous network dispersed throughout the epithelium and underlying mucosa of the conducting airways. Most of the available information on these cells comes from studies on tissues from experimental animals; however, comparable networks of DCs have also been formally demonstrated in humans.1-3

      These populations of DCs in the lung and airway wall are now known to play a central role in the maintenance of immunological homeostasis in the respiratory tract (reviewed by Holt and Stumbles1). As the principal resident antigen presenting cells (APC) in these tissues under steady state conditions, they serve as the local “gatekeepers” of the immune system. The principal function of these DCs is surveillance for incoming (inhaled) antigens deposited on airway mucosal surfaces, which they sample principally via receptor mediated endocytosis.4 Resident airway cells perform this function avidly but are relatively inefficient in presenting these antigens to T cells, due principally to poor surface expression of co-stimulator molecules such as CD80/CD86 which are obligatory second signals for T cell activation. Maturation of DCs from antigen acquirers into antigen presenters normally does not occur until the cells emigrate from peripheral tissues (bearing the antigens they have acquired) into the T cell zones of regional lymph nodes.5 During or immediately after this migration they mature under the influence of a variety of different cytokines including interleukin (IL)-1, tumour necrosis factor (TNF)α, and IL-4, but in particular granulocyte-macrophage colony stimulating factor (GM-CSF) which appears to serve as the “master regulator” in this process.5 This functional maturation is readily …

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