An intersectional genetic cell depletion unravels the unique role of Th1-Treg cells in tumor immunity

The immune system comprises various cell types including regulatory T (Treg) cells, and their subsets. Since most of inducible depletion of immune cells for the functional analysis rely on a single protein or gene, it is no longer optimal for the analysis of cell subsets defined by multiple genes. Here we create the Cre- and Flp-double recombinase-dependent intersectional genetic VeDTR mouse system that can selectively label and inducibly deplete a subpopulation of Treg cells called T helper 1 (Th1)-Treg cells. Characterization of Th1-Treg cells using the VeDTR mice revealed the high resistance under oxidative stress, which was required for Th1-Treg cells to accumulate in tumor tissues. Moreover, short-term depletion of Th1-Treg cells only led to anti-tumor immunity but not autoimmunity, whereas that of whole Treg cells did both. Collectively, we have established a novel intersectional genetic immune cell depletion system to reveal unique features of Th1-Treg cells in tumor immunity. Overall design: To characterize the difference between Th1-Treg cells and non-Th1-Treg cells, we analyzed gene expression pattern of YFP+ CD4+ CD25+ T cells (YFP+ Treg cells) and YFP- CD4+ CD25+ T cells (YFP- Treg cells) in the spleens of Foxp3-Cre/Tbx21-Flp/VeDTR(LF) mice.