Characterization of respiratory dendritic cells from equine lung tissues

BACKGROUND Dendritic cells (DCs) are professional antigen-presenting cells that have multiple subpopulations with different phenotypes and immune functions. Previous research demonstrated that DCs have strong potential for anti-viral defense in the host. However, viruses including alphaherpesvirinae have developed strategies to interfere with the function or maturation of DCs, causing immune dysfunction and avoidance of pathogen elimination. The goal of the present study was to isolate and characterize equine lung-derived DCs (L-DCs) for use in studies of respiratory viruses and compare their features with equine blood-derived DCs (B-DCs), which are currently used for these types of studies. RESULTS We found that L-DCs were morphologically similar to B-DCs. Overall, B-DCs demonstrated higher expression of CD86 and CD172α than L-DCs, but both cell types expressed high levels of MHC class II and CD44, as well as moderate amounts of CD163, CD204, and Bla36. In contrast, the endocytic activity of L-DCs was elevated compared to that of B-DCs. Finally, mononuclear cells isolated from lung (L-MCs), which are used as precursors for L-DCs, expressed more antigen-presenting cell-associated markers such as MHC class II and CD172α compared to their counterparts from blood. CONCLUSIONS Our results indicate that L-DCs may be in an earlier differentiation stage compared to B-DCs. Concurrent with this observation, L-MCs possessed significantly more antigen-uptake capacity compared to their counterparts from blood. It is likely that L-DCs play an important role in antigen uptake and processing of respiratory pathogens and are major contributors to respiratory tract immunity and may be ideal tools for future in vitro or ex vivo studies.