CD38 expression on multiple myeloma cells and plasma cells induced by CD27 signaling and IL-10. (A) Freshly isolated bone marrow cells from a multiple myeloma patient were stained by the combination of anti-CD38-FITC, anti-CD20-PE, and anti-CD27-PE. (B) Highly purified B cells were cultured with 100 ng/mL IL-10 for 8 days in the presence of mock transfectants, CD70 transfectants, or CD70 transfectants + anti-CD70 MoAb. Then, the cells were stained with anti-CD38-FITC and anti-CD20-PE. Antibody-coated cells, gated on live cells by cell size and granularity, and removed dead cells by propidium iodide staining, were enumerated by flow-cytometric analysis.