Generation of plasma cells from CD27⁺ B cells. Peripheral blood B cells were separated into CD27⁺(•) and CD27⁻ B cells (○) by a cell sorter and then incubated with IL-10 in the presence of mock transfectants, CD70 transfectants, or anti-CD40 MoAb for 8 days, and two-color analysis using anti-CD38-FITC and anti-CD20-PE was performed by flow cytometry. Percentages represent a ratio of highly expressed CD38⁺cells. The results are representative of four experiments. Horizontal bars represent the mean values.