Langerhans cells (LCs) constitute a subset of DCs that initiate immune responses in skin. Using leprosy as a model, we investigated whether expression of CD1a and langerin, an LC-specific C-type lectin, imparts a specific functional role to LCs. LC-like DCs and freshly isolated epidermal LCs presented nonpeptide antigens of Mycobacterium leprae to T cell clones derived from a leprosy patient in a CD1a-restricted and langerin-dependent manner. LC-like DCs were more efficient at CD1a-restricted antigen presentation than monocyte-derived DCs. LCs in leprosy lesions coexpress CD1a and langerin, placing LCs in position to efficiently present a subset of antigens to T cells as part of the host response to human infectious disease.
Robert E. Hunger, Peter A. Sieling, Maria Teresa Ochoa, Makoto Sugaya, Anne E. Burdick, Thomas H. Rea, Patrick J. Brennan, John T. Belisle, Andrew Blauvelt, Steven A. Porcelli, Robert L. Modlin
LCs express both CD1a and langerin in vivo. (A) Expression of langerin (left panels), CD1a (middle panels), and CD1b (right panels) in the epidermis (upper panels) and the dermis (lower panels) of the skin lesion of a leprosy patient. The images represent sections from the lesion of one patient showing the same region of the epidermis (upper panels) and the same granuloma (lower panels). Original magnification, ×200. (B) Colocalization of langerin and CD1a in the epidermis of a leprosy skin lesion. The dotted line indicates the margin between the epidermis (top) and the dermis (bottom). Original magnification, ×200.