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Functional defect in cells involved in Langerhans cell histiocytosis
1Unit of Dermatology, Royal Postgraduate Medical School, Hammersmith Hospital, London, UK.
Insights
Langerhans cell histiocytosis (LCH) cells exhibit defective immune function, showing minimal alloantigen-presenting activity compared to normal Langerhans cells. This suggests LCH is a condition of functionally impaired cells accumulating in tissues.
Area of Science:
- Immunology
- Cell Biology
- Histiocytosis
Background:
- Langerhans cell histiocytosis (LCH) is characterized by abnormal Langerhans cells (LCH cells).
- While LCH cells share markers with normal epidermal Langerhans cells, their functional capabilities remain unclear.
- Understanding LCH cell function is crucial for disease pathogenesis research.
Purpose of the Study:
- To investigate the alloantigen-presenting activity of LCH cells.
- To compare the functional capacity of LCH cells with normal epidermal Langerhans cells.
- To explore potential mechanisms underlying LCH cell dysfunction.
Main Methods:
- LCH cells were isolated from patient lesions and enriched using fluorescence-activated cell sorting or immunomagnetic beads.
- Alloantigen-presenting activity was assessed via a primary allogeneic mixed-cell reaction.
- Functional assays included testing responses to prostaglandin synthetase inhibitors and IL-1 beta.
Main Results:
- LCH cells demonstrated significantly reduced alloantigen-presenting activity per cell compared to normal epidermal Langerhans cells.
- This diminished function was not restored by prostaglandin synthetase inhibitors or IL-1 beta.
- Findings confirm previous reports of functionally defective LCH cells.
Conclusions:
- LCH cells possess a functionally defective phenotype, with impaired alloantigen presentation.
- The study supports the hypothesis that LCH results from the accumulation/proliferation of these functionally deficient cells.
- A primary defect in LCH cells, possibly due to an unknown biological insult, is postulated.
Abstract:
The characteristic cell type involved in Langerhans cell histiocytosis, 'LCH cells', express most of the enzyme histochemical and immunocytochemical markers of normal epidermal Langerhans cells. It is not known, however, whether these LCH cells express the functional characteristics of normal epidermal Langerhans cells. We studied the alloantigen-presenting activity of LCH cells derived from lesional sites of three patients with the disease. Lesional cells expressing the CD1a molecule were enriched using either fluorescein-activated cell sorting or negative selection with indirect immunomagnetic beads, and functional activity was assessed using the 6-day primary allogeneic mixed-cell reaction. Compared to epidermal Langerhans cells from healthy controls, LCH cells showed minimal alloantigen-presenting activity on a per-cell basis. The diminished activity was not reversed by exogenous prostaglandin synthetase inhibitor or recombinant human IL-1 beta. This study confirms our previous report of a child, with fatal multisystem Langerhans cell histiocytosis suggesting that this disease represents a condition in which functionally defective cells of Langerhans cell phenotype accumulate and/or proliferate in various tissues. We postulate that the functional defect is a primary defect of these LCH cells that have acquired an as-yet-undetermined biological insult(s).