Experimental Animal Division

Tracking and depletion of XCR1-positive dendritic cells

B6.Cg-Xcr1<tm2(HBEGF/Venus)Ksho>  (XCR1-DTRvenus mice, RBRC09485)

B6.Cg-Xcr1<tm1Ksho>  (XCR1-venus, RBRC09486)

Courtesy of Tsuneyasu Kaisho, M.D., Ph.D.

(a) Schematic representation of the mouse wildtype Xcr1 allele, targeting vectors, and knocked-in alleles. Filled and open boxes denote coding and non-coding exons of Xcr1, respectively. DTR, Neo^r, and HSV-tk represent human diphtheria toxin receptor gene, neomycin-resistance gene, and herpes simplex virus thymidine kinase gene. (b) Venus expression and inducible depletion of XCR1⁺ DCs in XCR1-DTRvenus mice. Venus is expressed in murine CD8α⁺103⁺11b^– DCs and the venus-expressing DCs are depleted one day after injection of diphtheria toxin. Numbers represent percentages of gated cells. (c) Venus expression levels of XCR1-DTRvenus and XCR1-venus mice. XCR1-venus mice show much higher expression levels of venus than XCR1-DTRvenus mice. (d) Venus expression (green) of XCR1-venus mice. A Peyer’s patch is observed by stereo-microscope (upper panel). A cryosection of an inguinal lymph node is stained with anti-B220 antibody (red) (lower). Venus expression can be detected without any anti-venus Abs.

Dendritic cells (DCs) are professional antigen-presenting cells that play an important role in linking innate and adaptive immunity. DCs are heterogeneous and can be divided into several subsets, such as CD8α⁺103⁺11b^– and CD8α^–103^–11b⁺ DCs, which are functionally distinct. DCs expressing a chemokine receptor, XCR1, are found in CD8α⁺103⁺11b^– subset of DCs not only in the spleen but also in lymph nodes or peripheral tissues such as skin or intestine and show high ability to cross-present antigens on MHC class I molecules to initiate cytotoxic CD8⁺ T cell responses. Human XCR1 is also dominantly expressed in CD141⁺ DCs, which are featured by the crosspresenting ability and considered to be a human homologue of murine CD8α⁺103⁺11b^– DCs. Therefore XCR1 is considered to be a marker for the crosspresenting DC subset in both mouse and human [1]. Kaisho and colleagues generated mouse strains to track and deplete XCR1⁺ DCs by knocking the genes encoding for a YFP derivative Venus or a fusion protein of human diphtheria toxin receptor (DTR) and venus into the Xcr1 locus [2]. XCR1⁺ DCs can be tracked by venus expression in both XCR1-DTRvenus (Xcr1-+/DTR-venus) and XCR1-venus (Xcr1-+/venus) mice. In terms of venus expression level, XCR1-venus mice are much more superior than XCR1-DTRvenus mice. In XCR1-DTRvenus mice, XCR1⁺ DCs can be transiently depleted by injection of diphtheria toxin, which cause cell death through human DTR. Thus, both XCR1-venus and XCR1-DTRvenus mice are useful tools to elucidate in vivo behavior and functions of XCR⁺ DCs in lymph nodes and peripheral tissues.