A fluorescent reporter model for the visualization and characterization of T_DC

T_DC are hematopoietic cells that combine dendritic cell (DC) and conventional T-cell markers and functional properties. They were identified in secondary lymphoid organs (SLOs) of naïve mice as cells expressing CD11c, major histocompatibility molecules (MHC)-II, and the T-cell receptor (TCR). Despite thorough characterization, a physiological role for T_DC remains to be determined. Unfortunately, using CD11c as a marker for T_DC has the caveat of its upregulation on different cells, including T cells, upon activation. Here, we took advantage of Zbtb46-GFP reporter mice to explore the frequency and localization of T_DC in different tissues at steady state and upon viral infection. RNA sequencing analysis confirmed that T_DC sorted from Zbtb46-GFP mice have a gene signature that is distinct from conventional T cells and DC. In addition, this reporter model allowed for identification of T_DC in situ not only in SLOs but also in the liver and lung of naïve mice. Interestingly, we found that T_DC numbers in the SLOs increased upon viral infection, suggesting that T_DC might play a role during viral infections. In conclusion, we propose a visualization strategy that might shed light on the physiological role of T_DC in several pathological contexts, including infection and cancer.