Tunable chemokine production by antigen presenting dendritic cells in response to changes in regulatory T cell frequency in mouse reactive lymph nodes

• Published in: PloS one 2009-11, Vol.4 (11), p.e7696-e7696
• Main Authors: Dal Secco, Valentina, Soldani, Cristiana, Debrat, Claire, Asperti-Boursin, François, Donnadieu, Emmanuel, Viola, Antonella, Sarukhan, Adelaida
• Format: Article
• Language: English
• Subjects: Animals; Antigen-Presenting Cells - cytology; Antigens; Autoimmune diseases; B cells; CCL3 protein; Cell activation; Cell interactions; Cell Proliferation; Chemokine CCL2 - metabolism; Chemokine CCL3 - metabolism; Chemokines; Chemokines - metabolism; Cytokines; Dendritic cells; Dendritic Cells - cytology; Disease; Experiments; Gene Expression Regulation; Immune response; Immunoglobulins; Immunology; Immunology/Immune Response; Immunology/Leukocyte Activation; Immunoregulation; Inflammation; Influenza; Laboratory animals; Laser microscopy; Ligands; Lymph nodes; Lymph Nodes - metabolism; Lymph Nodes - pathology; Lymphatic system; Lymphocyte Activation; Lymphocytes; Lymphocytes T; Mice; Mice, Inbred BALB C; Mice, Transgenic; Microscopy; Models, Biological; Monocyte chemoattractant protein 1; Organs; Priming; Regulation; Rodents; T cell receptors; T cells; Transgenic animals
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0007696

Although evidence exists that regulatory T cells (Tregs) can suppress the effector phase of immune responses, it is clear that their major role is in suppressing T cell priming in secondary lymphoid organs. Recent experiments using two photon laser microscopy indicate that dendritic cells (DCs) are central to Treg cell function and that the in vivo mechanisms of T cell regulation are more complex than those described in vitro. Here we have sought to determine whether and how modulation of Treg numbers modifies the lymph node (LN) microenvironment. We found that pro-inflammatory chemokines -- CCL2 (MCP-1) and CCL3 (MIP-la) -- are secreted in the LN early (24 h) after T cell activation, that this secretion is dependent on antigen-specific DC-T cell interactions, and that it was inversely related to the frequency of Tregs specific for the same antigen. Furthermore, we demonstrate that Tregs modify the chemoattractant properties of antigen-presenting DCs, which, as the frequency of Tregs increases, fail to produce CCL2 and CCL3 and to attract antigen-specific T cells. These results substantiate a major role of Tregs in LN patterning during antigen-specific immune responses.