Bidirectional interactions between antigen-bearing respiratory tract dendritic cells (DCs) and T cells precede the late phase reaction in experimental XXXX : DC activation occurs in the airway mucosa but not in the lung parenchyma.

@entity2937 @entity565 @entity1358 @entity1030 @entity1412
The airway mucosal response to allergen in @entity565 involves influx of activated T helper type 2 cells and eosinophils, transient @entity1030 , and airways hyperresponsiveness (AHR). The mechanism(s) underlying transient T cell activation during this inflammatory response is unclear. We present evidence that this response is regulated via bidirectional interactions between airway mucosal dendritic cells (AMDC) and T memory cells. After aerosol challenge, resident AMDC acquire antigen and rapidly mature into potent @entity1358 ( @entity1358 ) after cognate interactions with T memory cells. This process is restricted to dendritic cells (DCs) in the mucosae of the conducting airways, and is not seen in peripheral lung. Within 24 h, antigen-bearing mature DCs disappear from the airway wall, leaving in their wake activated interleukin 2R+ T cells and AHR. Antigen-bearing activated DCs appear in regional lymph nodes at 24 h, suggesting onward migration from the airway. Transient up-regulation of @entity2937 on AMDC accompanies this process, which can be reproduced by coculture of resting AMDC with T memory cells plus antigen. The @entity1412 activity of AMDC can be partially inhibited by anti- @entity2937 , suggesting that @entity2937 may play an active role in this process and/or is a surrogate for other relevant costimulators. These findings provide a plausible model for local T cell activation at the lesional site in @entity565 , and for the transient nature of this inflammatory response.
