The pDCs in bone marrow are homogeneous with respect to most lympho-hematopoietic–cell antigens and represent a conspicuous subset of Fraction A. (A) Purified B220⁺CD19^-Ly-6C⁺CD11c^Lo BM pDCs were labeled with the indicated cell surface markers and analyzed by flow cytometry. Dashed lines indicate isotype controls. (B) BALB/c wBM was stained for CD45R/B220, CD43, and CD19. CD45R/B220⁺CD43⁺CD19^- cells were gated and sorted as indicated with boxes (i). The recovered cells (middle panel) were then stained with CD24 and resorted as B220⁺CD43⁺CD19^-CD24^-/Lo (Fraction A; ii). Sorted Fraction A cells were then stained and analyzed with respect to CD11c and Ly6C to discriminate B220⁺CD19^-Ly-6C⁺CD11c^Lo pDCs among B220⁺CD43⁺CD19^-CD24^-/Lo Fraction A cells. (iii) Total numbers of pDCs (▪) and total Fraction A cells (▦) recovered from 4 harvested bones from 3 strains of mice are shown in the bar graph. Results are presented as the mean ± SD of 5 different experiments.