HLA-DQA2 and HLA-DQB2 genes are specifically expressed in human Langerhans cells and encode a new HLA class II molecule.

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.

The assembly of CD1e is controlled by an N-terminal propeptide which is processed in endosomal compartments.

CD1e displays unique features in comparison with other CD1 proteins. CD1e accumulates in Golgi compartments of immature dendritic cells and is transported directly to lysosomes, where it is cleaved into a soluble form. In these latter compartments, CD1e participates in the processing of glycolipid antigens.

HLA class I deficiency syndrome mimicking Wegener's granulomatosis.

Herein we report the case of a 20-year-old woman who presented with multiple skin ulcers on her legs, severe pansinusitis, and chronic lung disease. She was initially thought to have Wegener's granulomatosis (WG). However, serologic studies indicated an HLA class I deficiency, which was confirmed by flow cytometry.

Control of the intracellular pathway of CD1e.

CD1e is a membrane-associated protein predominantly detected in the Golgi compartments of immature human dendritic cells. Without transiting through the plasma membrane, it is targeted to lysosomes (Ls) where it remains as a cleaved and soluble form and participates in the processing of glycolipidic antigens. The role of the cytoplasmic tail of CD1e in the control of its intracellular pathway was studied.

A novel mutation for TAP deficiency and its possible association with Toxoplasmosis.

We describe two siblings (a male patient and his older sister) with a novel mutation in the peptide transporter associated to antigen processing (TAP). The index case presented with not only granulomatous skin lesions and recurrent sino-pulmonary infections, often associated with this deficiency, but also a severe pulmonary toxoplasmosis. His toxoplasmosis and skin lesions were successfully treated.

The cellular pathway of CD1e in immature and maturing dendritic cells.

Dendritic cells (DCs) present antigens to T cells via CD1, HLA class I or class II molecules. During maturation, HLA class II-restricted presentation is optimized. The relocalization of CD1e from Golgi to endosomal compartments during DC maturation suggests also an optimization of the antigen-presentation pathway via CD1 molecules.

Reproduction of Langerin/CD207 traffic and Birbeck granule formation in a human cell line model.

Birbeck granules (BG) are organelles specific to Langerhans cells (LCs), which form where the C-type lectin Langerin accumulates. Their function remains obscure due to morphologic and dynamic alterations induced by maturation of isolated LC. In this study, we attempted to reconstitute Langerin traffic and BG formation in the endosomal pathway of a human melanoma cell line.

Common characteristics of the human and rhesus macaque CD1e molecules: conservation of biochemical and biological properties during primate evolution.

In humans, a family of five genes encodes the CD1 molecules. Four of these proteins, CD1a, b, c, and d, are expressed on the plasma membrane and traffic between the cell surface and endocytic compartments, where they are loaded with antigenic glycolipids. The existence of human CD1e was demonstrated recently.