Langerhans Cell (LC)

  •    
     Be able to identify EM image of Langerhans cell 
       
    Bone marrow-derived dendritic cell with monocyte-macrophage lineage found in stratum spinosum; constitutes 3–5% of cells of epidermis; contains actin and vimentin
  • Critical in recognizing and presenting foreign antigens to specific T lymphocytes
  • Connected to keratinocytes via E-cadherin receptors
  • On EM, Langherhans cell with folded nucleus and distinct intracytoplasmic organelles (Birbeck granules: rod-shaped or tennis racquet-shaped with striated appearance)
  • Exposure to UV radiation causes depletion of LC and decreases ability to present antigen
   
 
Langerhans cell histiocytosis:
Letterer-Siwe – acute disseminated
Eosinophilic granuloma – bone (cranium)
Hand-Schuller-Christian – diabetes insipidus, exophthalmos, bone lesions
Hashimoto-Pritzker – self-healing