Langerhans cell
Epidermis · Spinous layer CD1a, langerin Antigen presenting
Bone-marrow-derived dendritic antigen-presenting cell forming a network mainly through the stratum spinosum. It samples antigen that penetrates the barrier, then migrates to the draining lymph node to prime naive T cells.
Detail
- Proportion
- About 2-8% of epidermal cells, forming a near-continuous surveillance network
- Markers
- CD1a and langerin (CD207) positive; langerin generates the cytoplasmic Birbeck granule
- Function
- Captures hapten or microbial antigen, matures, migrates via dermal lymphatics to the regional node and presents on MHC II — the sensitisation phase of allergic contact dermatitis
- Depletion
- Reduced by UVB, which is part of how phototherapy suppresses cutaneous immune responses
When it goes wrong
Hapten sensitisation (nickel, chromate in cement, para-phenylenediamine in hair dye)
Type IV delayed hypersensitivity: eczematous dermatitis appearing 48-72 hours after re-exposure, confirmed by patch testing read at 48 and 96 hours
Clonal proliferation of Langerhans cells, often BRAF V600E mutant (Langerhans cell histiocytosis)
CD1a and langerin positive infiltrate: lytic skull lesions, seborrhoeic-like scalp eruption, and posterior pituitary infiltration causing cranial diabetes insipidus
Practise this structure
16 questions in the bank tagged Skin.
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Mechanisms of disease · middle twist
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Mechanisms of disease · middle twist
A biopsy of the tracheal epithelium shows a single layer of cells with nuclei at different levels, cilia, and mucus-secreting goblet cells. Which of the followi…
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Which of the following is TRUE about stratified columnar epithelium?
Foundations · niche
Which function is performed by stratified cuboidal epithelium?
Foundations · common