STUDY OF TYPE I INTERFERON PRODUCING CELLS IN SHEEP LYMPH DRAINING ORO-NASAL MUCOSAE OR SKIN TISSUES

Interferons (IFN) are natural antiviral molecules produced by cells as an early response to a viral aggression. To study the early production of IFN at primary sites of viral infections (i.e. mucosal or skin tissues), we used a novel lymphatic cannulation model in sheep, providing real-time access to lymph and lymph cells draining a mucosal or skin area. Following oronasal or cutaneous injection of an IFN-inducing oligonucleotide, we were able to detect IFN early on in the lymph draining the injection site, as well as IFN-producing lymph cells migrating from the injection site to the draining lymph node. These rare cells (<1%) share the same features as plasmacytoid dendritic cells (low density, B-neg CD11c(neg) CD45RB(pos), expressing TLR7 and 9, and IRF7 transcripts). They play an important role in the activation of adaptive immunity, and could provide interesting targets for innovative vaccine strategies.