HLA-G expression on SP myeloma cells. (A) HLA-G expression on the side population content of plasma cells (CD38⁺⁺ CD138⁺) and the remaining non-SP plasma cells in a BM sample of a representative patient. (B) Ten patients with sufficient CD38⁺⁺ SP⁺ cells for analysis and with > 1% HLA-G expression were analyzed for HLA-G expression on CD38⁺⁺ SP cells and demonstrated a trend for higher HLA-G on SP cells (χ² = 5.0; P < .025).