Fig. 4.

Sirpα⁺ TcDCs originate from peripheral blood and can migrate into the thymus. (A) DC generation from purified Lineage⁻Thy-1^loc-kit⁺ intrathymic precursors (CD45.2) was analyzed 2 weeks after precursor transfer. The intrathymic precursor-derived cDCs were mainly CD8⁺Sirpα⁻ (Right). A representative contour plot of the normal TcDC subsets is shown (Left) for comparison. (B) White blood cells (20 × 10⁶) from CD45.1 mice were transferred i.v. into nonirradiated CD45.2 recipients. The phenotype of donor-derived cells in the thymus of recipients was determined 3 days later by gating for CD45.1⁺CD11c⁺CD45RA^lo cDCs. Expression of Sirpα, CD11b, CD8, and MHCII was determined on this population. (C–E) Thymic lobes from OTII tg CD45.2⁺ mice crossed to CD45.1⁺ WT mice were grafted under the kidney capsule of CD45.2⁺ CD11cOVA tg or WT recipients. (C) The phenotype of recipient-derived CD45.2⁺CD45.1⁻ DCs in the grafted thymic lobes from WT and CD11cOVA tg mice was determined. The recipient CD45.2⁺CD45.1⁻CD11c⁺CD45RA⁻ cDCs were gated for, and the expression of CD8 and Sirpα was determined. The level of expression of MHCII was determined on Sirpα⁻ and Sirpα⁺ cDCs. (D) The total number of CD45.1⁺CD4⁺Vα2⁺Vβ5⁺ cells (OTII) was calculated in OTII lobes grafted into WT or CD11cOVA tg recipients. Data are the mean of three independent experiments (error bars, ±SD) (n = 11–21). *, P < 0.05. (E) CD45.1⁺CD4⁺Vα2⁺Vβ5⁺ cells in the OTII lobes from WT and CD11cOVA tg recipients (as in D) were further analyzed for CD25 and Foxp3 expression. The total number of CD45.1⁺CD4⁺Vα2⁺Vβ5⁺CD25⁺Foxp3⁺ T_Rs was calculated. Data are the mean of three independent experiments (error bars, ±SD) (n = 11–21). *, P < 0.05.