Deficiency of CD4⁺ cDCs and mDCs in pLNs of SIRPα MT mice. (A-B) Cells prepared from pLNs of WT or SIRPα MT mice were incubated with a biotin-conjugated mAb to CD4. The cells were also stained with PE-conjugated streptavidin, an APC-conjugated mAb to CD11c, an APC-Cy7–conjugated mAb to B220, an FITC-conjugated mAb to CD8 or to I-A, and PI. The expression of CD11c and either B220 or I-A on PI-negative cells (A) and that of CD4 and CD8 on cDCs (B) were analyzed by 5-color flow cytometry (left panels). The relative numbers of cDCs, pDCs, or CD11c^int I-A^high mDCs are expressed as a percentage of all viable cells from pLNs in each plot (A), as are the relative numbers of CD8⁺, CD4⁺, or DN cDCs among all cDCs (B). The absolute numbers of cDCs, pDCs, and mDCs (A) or of CD8⁺, CD4⁺, or DN cDCs (B) in pLNs were also determined (right panels); data are means ± SE for 3 mice per group and are representative of 3 independent experiments. *P < .05, **P < .01 (Student t test). (C) A DC-enriched, low-density fraction of thymocytes from WT or SIRPα MT mice was incubated with a biotin-conjugated mAb to CD11b. The cells were also stained with an FITC-conjugated mAb to CD8, PE-conjugated streptavidin, an APC-conjugated mAb to CD11c, an APC-Cy7–conjugated mAb to B220, and PI. The expression of CD11b and CD8 on cDCs was analyzed by 5-color flow cytometry (left panel). The relative numbers of CD11b^high CD8⁻ and CD11b^low CD8⁺ cells are shown as a percentage of all viable cDCs of the thymus on each plot. The percentage of such CD8⁺ or CD8⁻ cDCs among viable cDCs was also determined (right panel); data are means ± SE for 3 mice of each group and are representative of 3 independent experiments.