Ontogeny of mouse splenic DC populations analyzed by flow cytometry. (A) Spleen DCs of BALB/c (A-F) or C57BL/6 (F) mice were analyzed from birth to adulthood for the expression of CD11c (A-C) together with B220 (D-E), CD4 (F), CD8α (F). (A) Day-1 spleen cells analyzed for CD11c and CD45RB. (B) Level of CD11c is shown for cells gated in panel A and taken from day-1 (gray) versus adult animal (bold line) cells. M1 and M2 gates define CD11c^high and CD11c^low DCs, respectively. (C) CD11c⁺ cells were analyzed at various ages for CD11c^high (□) and CD11c^low (▪) DC populations according to gating shown in panel B. (D) Gated CD11c⁺CD19^- cells were analyzed for B220 expression in day-1 (gray) versus adult spleen (bold line) cells. M3 defines B220⁺ cells. (E) The percentage of PDCs (B220⁺) in the spleen is shown at various ages according to gating shown in panel D. PDCs were CD11c^lowCD4^+/-CD8α^-CD19^-B220⁺CD45RB⁺Ly6C/G⁺MHCII^low at all developmental stages, but CD4 was poorly expressed early in life (not shown). □ represents B220^-; ▪, B220⁺. (F) At various ages, CD11c^high DCs from BALB/c and C57BL/6 mice were analyzed for CD4 and CD8α expression. Calculated percentages correspond to the mean of results obtained in 3 to 5 mice analyzed in the same experiment.