Phenotypic characterization of SLC-bearing B lineage cells in bone marrow.

(A) Human adult or fetal cells and (B) mouse cells from wild-type or Rag-2^−/− juvenile mice were incubated with, respectively, anti-CD19 or anti-B220 antibodies, plus digoxigenin-labeled anti-VpreB and antidigoxigenin-coated fluorochrome-loaded liposomes, before counterstaining with fluorochrome-labeled antibodies against CD34, μHC, or κ/λLC (A) or CD19, CD43, BP-1, or κ/λLC (B). Viable CD19⁺ cells (A) or B220⁺ cells (B) were electronically gated for this analysis. Coexpression of μHC by VpreB⁺ cells, indicated by the upward shift observed with conventional immunofluorescence (A, middle panels), was confirmed in parallel experiments in which the liposome-enhanced assay was also used to detect cell surface μHC expression (see text).