Identification of a novel population of Langerin+ dendritic cells. J Exp Med 204: 3147-56 Chen JS, Chiu HC, Hsu CJ et al. (2009) Lowenergy visible light irradiation modulates immune responses induced by epicutaneous sensitization with protein antigen. J Invest Dermatol 129:2258-64 Isacke CM (2002) Molecules in focus the hyaluronan receptor, CD44. Int J Biochem Cell Biol 34:718-21 Merad M, Ginhoux F, Collin M (2008) Origin, homeostasis and function of Langerhans cells and other langerin-expressing dendritic cells. Nat Rev Immunol 8:935-47 Mummert DI, Takashima A, Mummert ME (2004) Langerhans cells in CD44-deficient mice emigrate from the epidermis but fail to reach the lymph nodes after hapten application. J Invest Dermatol 122:846-7 Shklovskaya E, Roediger B, Fazekas de St Groth B (2008) Epidermal and dermal dendritic cells display differential activation and migratory behavior while sharing the ability to stimulate CD4+ T cell proliferation in vivo.

Basal cell carcinoma (BCC) is the most common skin malignancy encountered worldwide. We hypothesized that CXC chemokines, small cytokines involved in inducing directed leukocyte chemotaxis, could play a key role in the modulation of BCC growth. In this study, quantitative RT-PCR revealed that the chemokines CXCL9, 10, 11, and their receptor CXCR3 were significantly upregulated by an average 22.6-fold, 9.2-fold, 26.6-fold, and 4.9-fold, respectively in BCC tissue samples as compared with nonlesional skin epithelium. Immunohistochemistry analysis revealed that CXCR3, CXCL10, and CXCL11, but not CXCL9, colocalized with cytokeratin 17 (K17) in BCC keratinocytes. In addition, CXCR3 and its ligands were expressed in cells of the surrounding BCC stroma. The chemokines and K17 were also expressed in cultured human immortalized HaCaT keratinocytes. Exposure of HaCaT cells or primary BCCderived cells to CXCL11 peptides in vitro significantly increased cell proliferation. In primary BCC-derived cell cultures, addition of CXCL11 progressively selected for K17؉ /CXCR3 ؉ co-expressing cells over time. The expression of CXCR3 and its ligands in human BCC keratinocytes, the enhancement of keratinocyte cell proliferation by CXCL11, and the homogeneity of K17 ؉ BCC cells in human BCC-isolated cell population supported by CXCR3/CXCL11 signaling all suggest that CXCR3 and its ligands may be important autocrine and/or paracrine signaling mediators in the tumorigenesis of

Although the complete picture for alopecia areata (AA) pathogenesis has yet to be determined, recent research has made much progress in our understanding of the disease mechanism. Numerous circumstantial evidence supports the notion that AA is fundamentally a disease mediated by inflammatory cells and may be autoimmune in nature. Recent research has shown the hair-loss phenotype is precipitated predominantly by CD8+ lymphocytes, but the disease mechanism is driven by CD4+ lymphocytes. Although genetic susceptibility is a key contributor to disease development, disease onset and phenotypic presentation are probably modified by complex environmental interplay. On the basis of our current understanding of AA disease pathogenesis, several experimental and theoretical therapeutic approaches might be possible. However, the pathogenetic disease mechanism is particularly robust and the development of a cure for AA will be a significant challenge.

Immune privilege (IP) is believed to exist in the anagen hair follicle (HF). Studies have shown that downregulation of major histocompatibility complex Class I occurs and immunosuppressive factors are expressed in the HF bulb and bulge. However, demonstration and quantification of functional IP in HF cells are required. We examined the middle (sheath) and lower (bulb) portions of the human HF using quantitative real-time RT-PCR (qPCR), immunohistology, ELISA, in vitro coculture with peripheral blood mononuclear cells (PBMCs), and flow cytometry. We found that HF cells, relative to non-follicular epidermal cells, failed to promote allogeneic PBMC proliferation and CD4(+) and CD8(+) IFNγ production. By qPCR, we found significant downregulation of Class I and Class II HLA alleles in both the bulb and sheath, and upregulation of multiple immunoregulatory genes. It is noteworthy that somatostatin (SST) was significantly upregulated relative to epidermis. By immunohistochemistry, SST was most strongly expressed in the HF outer root sheath, and, by ELISA, cultured sheath cells secreted SST. PBMCs, cultured with stimulatory allogeneic epidermal cells and SST, secreted significantly less IFNγ than controls. Addition of SST antagonists to PBMCs cocultured with allogeneic HF cells increased IFNγ secretion. The data identify SST as a secretory factor potentially contributing to the HF IP repertoire.