Langerhans cells (LC) constitute a subset of dendritic cells (DC) that initiate innate immune responses in skin, and are able to instruct the acquired T cell response by the presentation of peptide antigen via MHC molecules. A unique aspect of LC is the co-expression of CD1a and the C-type lectin langerin. Through study of the skin lesions of leprosy, we discovered a unique function of LC: the ability to present microbial antigens by a langerin-dependent, CD1a-restricted pathway. In addition to their instructive role on acquired T cell responses, we demonstrated that LC have a direct innate function by their ability to induce an antiviral response. During the past three funding periods, in addition to investigating the role of LC in host defense against microbial infection, our studies have contributed to CD1 immunobiology, by defining the structure of lipid-containing CD1-restricted T cell antigens and mechanisms of CD1 antigen presentation, identified mechanisms that regulate CD1 expression in skin, and provided the first evidence for a direct T cell mediated antimicrobial activity. Based on our progress and preliminary data, we hypothesize that LC instruct the acquired T cell response by the langerin-dependent, CD1a-restricted presentation of lipoglycoprotein antigens to T cells and by a direct innate vitamin D-dependent antimicrobial pathway. We propose studies to advance our knowledge of LC and CD1 immunobiology, in relationship to host defense in skin, by investigating leprosy, an infection of skin caused by the obligate intracellular pathogen Mycobacterium leprae (mLEP).
Our specific aims are to 1) elucidate the structure of antigens presented by LC via CD1a to T cells, 2) determine the role of langerin in CD1a-restricted antigen presentation by LC to T cells;and 3) investigate the antimicrobial function of CD1- restricted T cells and LC in skin. The studies we propose are intended to provide a comprehensive and in depth view of LC and CD1-restricted T cell function in relation to a model of human skin disease, with the goal of understanding mechanisms of host defense to microbial pathogens in skin.

Public Health Relevance

Langerhans cells are resident cells of skin that participate in the immune responses. We propose to study leprosy as a model to gain insight into the mechanism by which Langerhans cells indirectly contribute to host defense against infection by the activation of T cells and directly mediate antimicrobial responses.

National Institute of Health (NIH)
National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS)
Research Project (R01)
Project #
Application #
Study Section
Arthritis, Connective Tissue and Skin Study Section (ACTS)
Program Officer
Cibotti, Ricardo
Project Start
Project End
Budget Start
Budget End
Support Year
Fiscal Year
Total Cost
Indirect Cost
University of California Los Angeles
Internal Medicine/Medicine
Schools of Medicine
Los Angeles
United States
Zip Code
Schenk, Mirjam; Fabri, Mario; Krutzik, Stephan R et al. (2014) Interleukin-1* triggers the differentiation of macrophages with enhanced capacity to present mycobacterial antigen to T cells. Immunology 141:174-80
Klug-Micu, Georgiana M; Stenger, Steffen; Sommer, Andrea et al. (2013) CD40 ligand and interferon-? induce an antimicrobial response against Mycobacterium tuberculosis in human monocytes. Immunology 139:121-8
Teles, Rosane M B; Graeber, Thomas G; Krutzik, Stephan R et al. (2013) Type I interferon suppresses type II interferon-triggered human anti-mycobacterial responses. Science 339:1448-53
Chung, Andrew W; Sieling, Peter A; Schenk, Mirjam et al. (2013) Galectin-3 regulates the innate immune response of human monocytes. J Infect Dis 207:947-56
Liu, Philip T; Wheelwright, Matthew; Teles, Rosane et al. (2012) MicroRNA-21 targets the vitamin D-dependent antimicrobial pathway in leprosy. Nat Med 18:267-73
Schenk, Mirjam; Krutzik, Stephan R; Sieling, Peter A et al. (2012) NOD2 triggers an interleukin-32-dependent human dendritic cell program in leprosy. Nat Med 18:555-63
Modlin, Robert L (2012) Innate immunity: ignored for decades, but not forgotten. J Invest Dermatol 132:882-6
Fabri, Mario; Realegeno, Susan E; Jo, Eun-Kyeong et al. (2011) Role of autophagy in the host response to microbial infection and potential for therapy. Curr Opin Immunol 23:65-70
Torrelles, Jordi B; Sieling, Peter A; Arcos, Jesus et al. (2011) Structural differences in lipomannans from pathogenic and nonpathogenic mycobacteria that impact CD1b-restricted T cell responses. J Biol Chem 286:35438-46
Fabri, Mario; Stenger, Steffen; Shin, Dong-Min et al. (2011) Vitamin D is required for IFN-gamma-mediated antimicrobial activity of human macrophages. Sci Transl Med 3:104ra102

Showing the most recent 10 out of 81 publications