Novel Process of Intrathymic Tumor-Immune Tolerance through CCR2-Mediated Recruitment of Sirpα+ Dendritic Cells: A Murine Model
Figure 2
Mice deficient in CCR2 gene exhibited reduced Treg differentiation and negative selection in the thymus.
(A) Schematic representation of localization and function of thymic Sirpα+ cDCs. OVA protein uptake by CD11chighSirpα+ cDCs in WT and CCR2−/− thymus at 4 hrs after injection are shown. Percentage of Sirpα (+) OVA647 (−) and Sirpα (+) OVA647 (+) region are shown in each panel. (B) The uptake of OVA647 by CD11c+Sirpα+ cDCs derived from C57BL/6 thymi at 4 hrs after injection is shown in left panel. Sirpα+ cDCs capturing OVA647 were separated into two groups according to the efficiency of OVA647 uptake; low and high. Percentages of cells in low and high regions in WT and CCR2−/− mice in BALB/c and C57BL/6 strain are shown in the right panel. Data represent mean ± SD from five and three independent experiments in BALB/c and C57BL/6 mice, respectively. (C) Expression of CD25 and Foxp3 on DO11.10high (R1) thymocytes at 2 days after OVA protein injection. Percentage of Foxp3 (+) region is shown in each panel. Representative results from three independent experiments are shown. (D) The numbers of Foxp3+ mature thymocytes were determined on DO11.10 and DO11.10/CCR2−/− mice at 2 days after OVA injection. Each symbol represents an individual mouse. Small horizontal lines indicate the mean. (E) Clonal deletion of thymocytes after OVA injection. Two mg OVA protein or heat-aggregated OVA protein were intravenously injected into DO11.10 mice. At 2 days after injection, the numbers of total thymocytes (left graph) and DP thymocytes (right graph) were determined on DO11.10 and DO11.10/CCR2−/− mice. Each symbol represents an individual mouse. **, p<0.01. *, p<0.05. N.S., no significant difference.