title: Tunable chemokine production by antigen presenting dendritic cells in response to changes in regulatory T cell frequency in mouse reactive lymph nodes.
abstract: BACKGROUND
  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.
  
  
  RESULTS
  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.
  
  
  CONCLUSIONS
  These results substantiate a major role of Tregs in LN patterning during antigen-specific immune responses.
authors.affiliation: Istituto Clinico Humanitas IRCCS, Milan, Italy.
authors.forename: Valentina
authors.initials: V
authors.lastname: Dal Secco
authors.forename: Cristiana
authors.initials: C
authors.lastname: Soldani
authors.forename: Claire
authors.initials: C
authors.lastname: Debrat
authors.forename: François
authors.initials: F
authors.lastname: Asperti-Boursin
authors.forename: Emmanuel
authors.initials: E
authors.lastname: Donnadieu
authors.forename: Antonella
authors.initials: A
authors.lastname: Viola
authors.forename: Adelaida
authors.initials: A
authors.lastname: Sarukhan
mesh_terms: D000818:Animals; D000938:Antigen-Presenting Cells / Q000166:cytology*; D049109:Cell Proliferation; D018932:Chemokine CCL2 / Q000378:metabolism; D054405:Chemokine CCL3 / Q000378:metabolism; D018925:Chemokines / Q000378:metabolism*; D003713:Dendritic Cells / Q000166:cytology*; D005786:Gene Expression Regulation; D007249:Inflammation; D008198:Lymph Nodes / Q000378:metabolism* / Q000473:pathology; D008213:Lymphocyte Activation; D051379:Mice; D008807:Mice, Inbred BALB C; D008822:Mice, Transgenic; D008954:Models, Biological
chemical_list: C491768:Ccl2 protein, mouse; C496534:Ccl3 protein, mouse; D018932:Chemokine CCL2; D054405:Chemokine CCL3; D018925:Chemokines