A category of pDCs residing in bone marrow expresses low levels of RAG1, as well as B-lineage–associated genes, and undergoes D_H-J_H rearrangements. (A) An uncompensated 2-parameter procedure was used to discriminate and sort GFP⁺ and GFP^- subsets of CD45R/B220⁺CD19^--enriched cells from BM of RAG1/GFP knock-in mice. The purified populations were then stained with Ly-6C and CD11c. The boxes in the bottom 2 histograms indicate gates used for an additional sorting of B220⁺CD19^-Ly-6C⁺CD11c^LoGFP⁺ and B220⁺CD19^-Ly-6C⁺CD11c^LoGFP^- pDC subsets. (B) RT-PCR analyses of the indicated genes were performed with cDNA prepared from these 2 sorted subsets and compared with B220⁺CD19⁺ CD43⁺CD24⁺ pro-B/large pre-B cells or to B220^-CD11c⁺ DCs, while β-actin was used as a loading control. (C) Genomic DNA from these same fractions was evaluated for Ig D_HJ_H and V_H-DJ_H rearrangements and germ-line loci by PCR. Specific products with the expected sizes are labeled with respect to rearrangement to J1, J2, or J3. Alpha actin was used as a control for genome representation.