The characterization of human dendritic cell (DC) subsets is essential for the design of new vaccines. We report the first detailed functional analysis of the human CD141+ DC subset. CD141+ DCs are found in human lymph nodes, bone marrow, tonsil, and blood, and the latter proved to be the best source of highly purified cells for functional analysis. They are characterized by high expression of toll-like receptor 3, production of IL-12p70 and IFN-β, and superior capacity to induce T helper 1 cell responses, when compared with the more commonly studied CD1c+ DC subset. Polyinosine-polycytidylic acid (poly I:C)–activated CD141+ DCs have a superior capacity to cross-present soluble protein antigen (Ag) to CD8+ cytotoxic T lymphocytes than poly I:C–activated CD1c+ DCs. Importantly, CD141+ DCs, but not CD1c+ DCs, were endowed with the capacity to cross-present viral Ag after their uptake of necrotic virus-infected cells. These findings establish the CD141+ DC subset as an important functionally distinct human DC subtype with characteristics similar to those of the mouse CD8α+ DC subset. The data demonstrate a role for CD141+ DCs in the induction of cytotoxic T lymphocyte responses and suggest that they may be the most relevant targets for vaccination against cancers, viruses, and other pathogens.
Conclusion. These clinical data suggest for the first time that IL-15 could represent a novel therapeutic target in RA.
+subsets that display unique gene expression profiles, suggesting specialized functions. CD1c+ DCs express TLR4 while CD141 + DCs do not, thus predicting that these two subsets have differential capacities to respond to Escherichia coli. We isolated highly purified CD1c + and CD141 + DCs and compared them to in vitro generated monocyte-derived DCs (MoDCs) following stimulation with whole E. coli. As expected, MoDCs produced high levels of the proinflammatory cytokines TNF, IL-6, and IL-12, were potent inducers of Th1 responses, and processed E. coli-derived Ag. In contrast, CD1c + DCs produced only low levels of TNF, IL-6, and IL-12 and instead produced high levels of the anti-inflammatory cytokine IL-10 and regulatory molecules IDO and soluble CD25. Moreover, E. coli-activated CD1c + DCs suppressed T-cell proliferation in an IL-10-dependent manner. Contrary to their mouse CD8 + DC counterparts, human CD141 + DCs did not phagocytose or process E. coli-derived Ag and failed to secrete cytokines in response to E. coli. These data demonstrate substantial differences in the nature of the response of human blood DC subsets to E. coli. Keywords: E. coli r Human dendritic cells r IL-10 See accompanying Commentary by Qian and CaoSupporting Information available online IntroductionDCs are potent antigen-presenting cells that play a fundamental role in the induction and regulation of innate and adaptiveCorrespondence: Dr. Kristen J. Radford e-mail: kradford@mmri.mater.org.au immune responses against microbial pathogens. DCs detect microbial products using a sophisticated repertoire of PRR that include the toll-like receptors (TLRs), nucleotide-binding oligomerization domain (NOD)-like receptors, retinoic acid * These authors contributed equally to this work.C 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim www.eji-journal.eu Eur. J. Immunol. 2012. 42: 1512-1522 Immunity to infection 1513 inducible gene 1 (RIG-I)-like receptors and C-type lectins. The nature of the immune response to a given pathogen is tightly regulated by the DC network, which consists of multiple subsets that are equipped with unique PRRs and are endowed with specialized functions. DCs in humans and mice can be categorized into three broad subtypes. These three subtypes are: (i) inflammatory DCs that are mobilized rapidly from monocytes in response to infection and inflammation (monocyte-derived DCs; MoDCs), (ii) migratory DCs that reside in the peripheral tissues and migrate to lymphoid tissues after encounter with Ag, and (iii) the blood and lymphoid tissue resident DCs that are comprised of plasmacytoid and myeloid DCs [1]. Further complexity arises within the steadystate myeloid DC subsets, which in humans are defined as lineage (CD3,14,15,19,20,56 ResultsMoDCs are the main DC subset responsive to E. coli CD1c + and CD141 + DCs were enriched from healthy donor leukapheresis products by immuno-magnetic selection, and flow sorted to high purity (>99%) using our established human DC isolation protocols [8,19]. Autologous MoDCs were differentiated from...
Dendritic cells (DCs) comprise heterogeneous subsets of professional antigen-presenting cells, linking innate and adaptive immunity. Analysis of DC subsets has been hampered by a lack of specific DC markers and reliable quantitation assays. We characterised the immunophenotype and functional characteristics of psoriatic arthritis (PsA)-derived and rheumatoid arthritis (RA)-derived myeloid DCs (mDCs) and plasmacytoid DCs (pDCs) to evaluate their potential role in arthritis. Circulating peripheral blood (PB) pDC numbers were significantly reduced in PsA patients (P = 0.0098) and RA patients (P = 0.0194), and mDCs were significantly reduced in RA patients (P = 0.0086) compared with healthy controls. The number of circulating mDCs in RA PB was significantly inversely correlated to C-reactive protein (P = 0.021). The phenotype of both DC subsets in PsA PB and RA PB was immature as compared with healthy controls. Moreover, CD62L expression was significantly decreased on both mDCs (PsA, P = 0.0122; RA, P = 0.0371) and pDCs (PsA, P = 0.0373; RA, P = 0.0367) in PB. Both mDCs and pDCs were present in PsA synovial fluid (SF) and RA SF, with the mDC:pDC ratio significantly exceeding that in matched PB (PsA SF, P = 0.0453; RA SF, P = 0.0082). pDCs isolated from RA SF and PsA SF displayed an immature phenotype comparable with PB pDCs. RA and PsA SF mDCs, however, displayed a more mature phenotype (increased expression of CD80, CD83 and CD86) compared with PB mDCs. Functional analysis revealed that both SF DC subsets matured following toll-like receptor stimulation. pDCs from PB and SF produced interferon alpha and tumour necrosis factor alpha on TLR9 stimulation, but only SF pDCs produced IL-10. Similarly, mDCs from PB and SF produced similar tumour necrosis factor alpha levels to TLR2 agonism, whereas SF mDCs produced more IL-10 than PB controls. Circulating DC subset numbers are reduced in RA PB and PsA PB with reduced CD62L expression. Maturation is incomplete in the inflamed synovial compartment. Immature DCs in SF may contribute to the perpetuation of inflammation via sampling of the inflamed synovial environment, and in situ presentation of arthritogenic antigen.
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