Analysis of the MHC class I and class II molecule expression on HSCs. (A) B10.BR bone marrow cells were stained (Sca-1⁺/c-Kit⁺/Lin^-) and gated for HSCs as lineage marker negative (lower left panel) and Sca-1⁺/c-Kit⁺ (lower right panel). (B) Expression of class I or class II MHC markers on HSCs was determined. Vertical dashed line indicates negative staining from isotype control. A minimum of 500 000 total events was collected for each histogram. FSC indicates forward scatter; SSC, side scatter.