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CD1 gene expression in human skin
J T Elder1, N J Reynolds, K D Cooper
1Department of Dermatology, University of Michigan, Ann Arbor 48109-0672.
Insights
CD1a and CD1c molecules are expressed in human skin. This study found that cell surface exclusion does not explain selective CD1c expression in the dermis, challenging previous hypotheses.
Area of Science:
- Immunology
- Dermatology
- Cell Biology
Background:
- CD1a expression is restricted to Langerhans cells (LC) in human epidermis.
- CD1c expression is found in dermal and epidermal dendritic cells.
- Transfected fibroblasts suggest CD1c cell surface expression may exclude CD1a/CD1b.
Purpose of the Study:
- To investigate if cell surface exclusion mechanism regulates CD1c expression in human skin.
- To compare surface expression of CD1a and CD1c with their mRNA levels in dermal and epidermal dendritic cells.
Main Methods:
- Dual-label immunofluorescence microscopy
- Northern blot hybridization
- Reverse transcriptase-polymerase chain reaction (RT-PCR)
- Immunomagnetic bead selection
Main Results:
- CD1c expression detected in both dermal and epidermal cells; CD1a mainly in epidermis.
- Epidermal LC express both CD1a and CD1c mRNA and surface proteins.
- Other epidermal cell types lack CD1a and CD1c expression.
Conclusions:
- Cell surface exclusion is not the mechanism for selective CD1c expression in human dermis.
- CD1a and CD1c expression patterns in human skin are complex and cell-specific.
Abstract:
In human epidermis, expression of CD1a is confined to Langerhans cells (LC), whereas CD1c expression has been observed in dendritic cells of the dermis, as well as the epidermis. In transfected fibroblasts, expression of CD1c at the cell surface appears to exclude expression of either CD1b or CD1a, despite continued transcription of the latter genes. In order to determine whether this mechanism might be operative in human skin, we have compared the expression of CD1a and CD1c on the surface of dermal and epidermal dendritic cells to their expression at the level of mRNA using a combination of dual-label immunofluorescence microscopy, northern blot hybridization, and reverse transcriptase-polymerase chain reaction (RT-PCR). By both immunofluorescence and Northern blotting, CD1c expression was observed in both dermal and epidermal cells, whereas expression of CD1a was confined largely to the epidermis. Moreover, as shown by immunomagnetic bead selection and RT-PCR, CD1a and CD1c were both expressed on epidermal LC, but were absent from other epidermal cell types. These results argue against cell surface exclusion as a mechanism for selective expression of CD1c in human dermis.