Figure 4.

XCR1 is functionally active on mouse CD8α⁺, human BDCA3⁺, and sheep CD26⁺ DCs, and Xcl1 mRNA is stored in quiescent NK cells and memory CD8⁺ T lymphocytes. Transwell migration assay on enriched human blood DCs or lymphocytes, sheep lymph CD26⁺ versus CD26⁻ DCs, and splenic DCs from XCR1^−/− and C57BL/6NCrl (XCR1^+/+) mice. Results are representative of at least two independent experiments for each species and expressed as mean ± SEM from duplicate wells for each data point. (B) Expression of the XCL1 gene in human and mouse cell types and tissues, based on the same gene chips data as used in Fig. 1 A, with the following additions: black triangles, NK cells; purple triangles, resting peripheral CD8⁺ T cells; purple diamond, anti-CD3 activated human T cells; purple square, mouse CD8⁺ thymocytes; violet square, mouse CD4⁺ thymocytes. Results are expressed as mean and SD for at least three independent values for most human data points. (C) Expression of the XCL1 gene in sheep leukocytes as assessed by real-time PCR on the same lymph or blood cells as shown in Fig. 2. Results are mean ± SEM of triplicate real-time RT-PCR reactions, and they are representative of two different sheep for lymphocytes and of three different sheep for DCs. (D) Results of Xcl1 gene expression in mouse CD8⁺ T cell subsets. Xcl1 expression was measured by real-time PCR on sorted naive or T_IM, or antiviral T_CM CD8⁺ T cell subsets. Expression of Ccl5 and Ifng were also evaluated as controls, as the genes are expressed to higher levels in memory CD8⁺ T cells (Walzer et al., 2003). Results are represented as mean ± SD for mean values from duplicate real-time PCR reactions performed on mRNAs from naive T cells or from T_IM from three individual mice each, and from T_CM from four individual pools of seven mice.