Definition of DC subpopulations from the spleen, Peyer’s patches, LN, and skin of the mouse. Contour plots show the CD8 versus CD11c, DEC-205, LFA-1, or Mac-1 profile of uncultured DC purified from the spleen, Peyer’s patches, mesenteric and peripheral LN, and skin of BALB/C mice, gated for CD11c⁺ cells. CD8⁺and CD8⁻ DC subpopulations can be defined (A and B) in the spleen . In the Peyer’s patches most DC are of the CD8⁺ subset. In the LN an additional CD8^intDC subset exists (C), which can be further subdivided on the basis of the CD8 versus LFA-1 expression: in the mesenteric LN, around 50% CD8^int DC are CD8^int-high LFA-1^low(C1 cells) whereas the remaining 50% are CD8^int-lowLFA-1^int (C2 cells), whereas in peripheral LN, CD8^int DC constitute a single population of CD8^int-low LFA-1^int cells (C2′ cells) (see text for details). Finally, epidermal LC constitute a single DC subpopulation with a distinctive phenotype. The CD8 versus DEC-205 contour plot for the skin corresponds to LC after overnight incubation because, as indicated in Materials and Methods, trypsin treatment used during LC isolation causes partial DEC-205 degradation, which can be restored on culture at 37°C (see also Fig 2). These data are representative of five to eight experiments with similar results.