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Fc epsilon RI mediates IgE binding to human epidermal Langerhans cells
1Department of Dermatology I, University of Vienna Medical School, Austria.
Insights
Epidermal Langerhans cells (LC) bind immunoglobulin E (IgE) via the high-affinity Fc epsilon RI receptor. This binding is specific and confirms LC express functional Fc epsilon RI molecules.
Area of Science:
- Immunology
- Dermatology
- Cell Biology
Background:
- Epidermal Langerhans cells (LC) play a crucial role in skin immunity.
- The expression of receptors for immunoglobulin E (IgE) on LC is not fully understood.
- Previous studies suggested potential IgE-binding capabilities of LC.
Purpose of the Study:
- To investigate the specific receptor responsible for IgE binding on epidermal Langerhans cells.
- To determine if Langerhans cells express the high-affinity IgE receptor (Fc epsilon RI).
- To differentiate Fc epsilon RI expression from other Fc receptors on LC.
Main Methods:
- Immunohistochemistry using monoclonal antibodies against Fc epsilon RI, Fc epsilon RII/CD23, and Fc gamma RII/CD32.
- Indirect immuno-double-labeling techniques.
- Ultrastructural immunogold labeling.
- Polymerase chain reaction (PCR) to detect Fc epsilon RI chain transcripts.
- Tryptase gene expression analysis to rule out mast cell contamination.
Main Results:
- Monoclonal antibody 15-1 against Fc epsilon RI blocked IgE binding to LC.
- Fc epsilon RI-specific antibodies reacted with CD1a-positive epidermal cells, including those with Birbeck granules.
- PCR detected Fc epsilon RI alpha, beta, and gamma chain transcripts in LC-enriched epidermal cells.
- Tryptase transcripts were absent in LC-enriched preparations, confirming no mast cell contamination.
Conclusions:
- Epidermal Langerhans cells express functional Fc epsilon RI molecules on their surface.
- This expression is specific and mediated by the high-affinity IgE receptor.
- These findings elucidate a key mechanism for IgE interaction with skin immune cells.
Abstract:
In a recent series of experiments, we observed that epidermal Langerhans cells (LC) of healthy, non-atopic individuals have the capacity of specifically binding monomeric serum or myeloma IgE. IgE-binding to LC could neither be prevented by pre-incubation of the cryostat sections with monoclonal antibodies (MoAb) against either Fc epsilon RII/CD23 or Fc gamma RII/CD32 nor by the addition of excess amounts of lactose, but could be entirely abrogated by pre-incubation with the anti-Fc epsilon RI MoAb 15-1. A direct testing of the anti-Fc epsilon RI MoAb 15-1 and 19-1 on cryostat sections in an indirect immuno-double-labeling technique showed that, in contrast to eight different anti-Fc epsilon RII/CD23 MoAb, these MoAb react with the majority of CD1a-bearing epidermal cells. At an ultrastructural level, 15-1 immunogold-labeling in the epidermis was confined to the surface of cells exhibiting Birbeck granules. In further experiments, we were able to amplify by polymerase chain reaction (PCR) technology transcripts for the alpha, beta, and gamma chains of Fc epsilon RI from LC-enriched epidermal cells and dermal cells, but not from LC-depleted epidermal cells. Transcripts for the mast cell enzyme tryptase were exclusively found in dermal cell-derived RNA preparations, thus excluding a contamination of the LC-enriched epidermal cell preparations by dermal mast cells. Collectively, these data show that epidermal LC, but not other epidermal cells, express Fc epsilon RI molecules.