HLA-DQA2 and HLA-DQB2 genes are specifically expressed in human Langerhans cells and encode a new HLA class II molecule.
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Lenormand C, Bausinger H, Gross F, Signorino-Gelo F, Koch S, Peressin M, Fricker D, Cazenave JP, Bieber T, Hanau D, de la Salle H, Tourne S
HLA-DQA2 and HLA-DQB2 genes are specifically expressed in human Langerhans cells and encode a new HLA class II molecule.
J Immunol. 2012 Apr 15;188(8):3903-11. doi: 10.4049/jimmunol.1103048. Epub 2012 Mar 9.
- PubMed ID
- 22407913 [ View in PubMed]
- Abstract
The precise role of human epidermal Langerhans cells (LCs) in immune response is highly controversial. While studying the gene expression profile of these cells, we were intrigued to identify the HLA-DQB2 gene as potentially expressed in LCs. Despite a strong evolutionary conservation of their sequences, the concomitant expression of the poorly polymorphic HLA-DQA2/HLA-DQB2 genes, paralogous to the HLA-DQA1/HLA-DQB1 genes, has never been detected in any cell type. We confirmed by RT-PCR that the HLA-DQA2 and -DQB2 genes are both expressed in LCs, but not in monocyte-derived dendritic cells, or in blood CD1c(+) or plasmacytoid dendritic cells. The presence of the HLA-DQbeta2 chain in LCs could be demonstrated by Western blotting, whereas immunofluorescence revealed its localization in early endosomes. As in the case of other HLA class II molecules, the HLA-DQalpha2 and -DQbeta2 chains formed heterodimers that had to associate with the invariant chain to reach endosomal compartments. HLA-DQalpha2/beta2 heterodimers were expressed at the cell surface, where they could mediate staphylococcal superantigen stimulation of T cells. Interestingly, HLA-DQalpha2 and HLA-DQbeta1 chains formed mixed heterodimers which efficiently left the endoplasmic reticulum. These observations strongly suggest that the poorly polymorphic HLA-DQA2 and -DQB2 genes should be considered to be of immunological importance. The HLA-DQalpha2/beta2 molecules could influence the complexity of the repertoire of Ags presented by LCs.