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Capacities of migrating CD1b+ lymph dendritic cells to present Salmonella antigens to naive T cells.

ABSTRACT: Dendritic cells (DCs) are well known as professional antigen-presenting cells (APC) able to initiate specific T-cell responses to pathogens in lymph nodes (LN) draining the site of infection. However, the respective contribution of migratory and LN-resident DCs in this process remains unclear. As DC subsets represent important targets for vaccination strategies, more precise knowledge of DC subsets able to present vaccine antigens to T cells efficiently is required. To investigate the capacities of DCs migrating in the lymph (L-DCs) to initiate a specific T-cell response, we used physiologically generated DCs collected from a pseudoafferent lymphatic cannulation model in sheep. The CD1b+ L-DCs were assessed for presenting antigens from the vaccine attenuated strain of Salmonella enterica serovar Abortusovis. CD1b+ L-DCs were able to phagocytose, process and to present efficiently Salmonella antigens to effector/memory T cells in vitro. They were shown to be efficient APC for the priming of allogeneic naive T cells associated with inducing both IFN-? and IL-4 responses. They were also efficient in presenting Salmonella antigens to autologous naive T cells associated with inducing both IFN-? and IL-10 responses. The capacities of L-DCs to process and present Salmonella antigens to T cells were investigated in vivo after conjunctival inoculation of Salmonella. The CD1b+ L-DCs collected after inoculation were able to induce the proliferative response of CD4+ T cells suggesting the in vivo capture of Salmonella antigens by the CD1b+ L-DCs, and their potential to present them directly to CD4+ T cells. In this study, CD1b+ L-DCs present potential characteristics of APC to initiate by themselves T cell priming in the LN. They could be used as target cells for driving immune activation in vaccinal strategies.

SUBMITTER: Olivier M

PROVIDER: S-EPMC3261196 | biostudies-literature | 2012

REPOSITORIES: biostudies-literature

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Capacities of migrating CD1b+ lymph dendritic cells to present Salmonella antigens to naive T cells.

Olivier Michel M Foret Benjamin B Le Vern Yves Y Guilloteau Laurence A LA

PloS one 20120118 1

Dendritic cells (DCs) are well known as professional antigen-presenting cells (APC) able to initiate specific T-cell responses to pathogens in lymph nodes (LN) draining the site of infection. However, the respective contribution of migratory and LN-resident DCs in this process remains unclear. As DC subsets represent important targets for vaccination strategies, more precise knowledge of DC subsets able to present vaccine antigens to T cells efficiently is required. To investigate the capacities ...[more]

PMID: 22279590

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Project description:Dendritic cells (DCs) are pivotal in the development of specific T-cell responses to control pathogens, as they govern both the initiation and the polarization of adaptive immunity. To investigate the capacities of migrating DCs to respond to pathogens, we used physiologically generated lymph DCs (L-DCs). The flexible polarization of L-DCs was analysed in response to Salmonella or helminth secretions known to induce different T cell responses. Mature conventional CD1b(+) L-DCs showed a predisposition to promote pro-inflammatory (IL-6), pro-Th1 (IL-12p40) and anti-inflammatory (IL-10) responses which were amplified by Salmonella, and limited to only IL-6 induction by helminth secretions. The other major population of L-DCs did not express the CD1b molecule and displayed phenotypic features of immaturity compared to CD1b(+) L-DCs. Salmonella infection reduced the constitutive expression of TNF-α and IL-4 mRNA in CD1b(-) L-DCs, whereas this expression was not affected by helminth secretions. The cytokine response of T cells promoted by L-DCs was analysed in T cell subsets after co-culture with Salmonella or helminth secretion-driven CD1b(+) or CD1b(-) L-DCs. T cells preferentially expressed the IL-17 gene, and to a lesser extent the IFN-γ and IL-10 genes, in response to Salmonella-driven CD1b(+) L-DCs, whereas a preferential IL-10, IFN-γ and IL-17 gene expression was observed in response to Salmonella-driven CD1b(-) L-DCs. In contrast, a predominant IL-4 and IL-13 gene expression by CD4(+) and CD8(+) T cells was observed after stimulation of CD1b(+) and CD1b(-) L-DCs with helminth secretions. These results show that mature conventional CD1b(+) L-DCs maintain a flexible capacity to respond differently to pathogens, that the predisposition of CD1b(-) L-DCs to promote a Th2 response can be oriented towards other Th responses, and finally that the modulation of migrating L-DCs responses is controlled more by the pathogen encountered than the L-DC subsets.

Project description:Immune recognition of vascular endothelial cells (EC) has been implicated in allograft rejection, protection against pathogens, and lymphocyte recruitment. However, EC pervade nearly all tissues and predominate in none, complicating any direct test of immune recognition. Here, we examined antigen presentation by EC in vivo by testing immune responses against E. coli beta-galactosidase (beta-gal) in two lines of transgenic mice that express beta-gal exclusively in their EC. TIE2-lacZ mice express beta-gal in all EC and VWF-lacZ mice express beta-gal in heart and brain microvascular EC.Transgenic and congenic wild type FVB mice immunized with beta-gal expression vector DNA or beta-gal protein generated high titer, high affinity antisera containing comparable levels of antigen-specific IgG1 and IgG2a isotypes, suggesting equivalent activation of T helper cell subsets. The immunized transgenic mice remained healthy, their EC continued to express beta-gal, and their blood vessels showed no histological abnormalities. In response to beta-gal in vitro, CD4+ and CD8+ T cells from immunized transgenic and FVB mice proliferated, expressed CD25, and secreted IFN-gamma. Infection with recombinant vaccinia virus encoding beta-gal raised equivalent responses in transgenic and FVB mice. Hearts transplanted from transgenic mice into FVB mice continued to beat and the graft EC continued to express beta-gal. These results suggested immunological ignorance of the transgene encoded EC protein. However, skin transplanted from TIE2-lacZ onto FVB mice lost beta-gal+ EC and the hosts developed beta-gal-specific antisera, demonstrating activation of host immune effector mechanisms. In contrast, skin grafted from TIE2-lacZ onto VWF-lacZ mice retained beta-gal+ EC and no antisera developed, suggesting a tolerant host immune system.Resting, beta-gal+ EC in transgenic mice tolerize specific lymphocytes that would otherwise respond against beta-gal expressed by EC within transplanted skin. We conclude that EC effectively present intracellular "self" proteins to the immune system. However, antigen presentation by EC does not delete or anergize a large population of specific lymphocytes that respond to the same protein following conventional immunization with protein or expression vector DNA. These results clearly demonstrate striking context sensitivity in the immune recognition of EC, a subtlety that must be better understood in order to treat immune diseases and complications involving the vasculature.

Dataset Information

Capacities of migrating CD1b+ lymph dendritic cells to present Salmonella antigens to naive T cells.

Publications

Capacities of migrating CD1b+ lymph dendritic cells to present Salmonella antigens to naive T cells.

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