ID: 244 : Eosinophil IL-13 polarizes CD11b+ CD103+ dendritic cells to initiate Th2 immune responses in the gut associated lymphoid tissue

Dendritic cells are key to the initiation and regulation of immune responses. In the gut there are three distinct dendritic cell (DC) subsets, defined by CD11b and CD103, each with different developmental requirements and distinct functional potential. Recent evidence has described a role for the different gut DC subsets in the generation of Th17 and Treg responses, but little is yet known of their contribution to the initiation of Th2 immune responses in the intestines. We used the nematode Heligmosomoides polygyrus to initiate a potent Th2 response in the small intestine. We found that during H. polygyrus infection CD11b+ CD103+ DC preferentially migrated from the site of infection to the local lymph node. These DC showed increased expression of PDL2 and had an enhanced capacity to prime naive CD4+ T cell toward Th2. Migration and activation of CD11b+ CD103+ DC was dependent on the cytokine IL-13, which was secreted by activated eosinophils at the site of infection. Together our data suggest that the initiation of a Th2 response in the intestines involves early activation of eosinophils, which secrete the cytokine needed to activate and mobilize Th2-driving DCs.