Tunable chemokine production by antigen presenting dendritic cells in response to changes in regulatory T cell frequency in mouse reactive lymph nodes.
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.
Dal Secco
Valentina
V
Istituto Clinico Humanitas IRCCS, Milan, Italy.
Soldani
Cristiana
C
Debrat
Claire
C
Asperti-Boursin
François
F
Donnadieu
Emmanuel
E
Viola
Antonella
A
Sarukhan
Adelaida
A
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
C491768:Ccl2 protein, mouse; C496534:Ccl3 protein, mouse; D018932:Chemokine CCL2; D054405:Chemokine CCL3; D018925:Chemokines