Phenotypic changes during the differentiation of PB B cells into plasmablastic cells.

(A) Purified CD19⁺ PB B cells were single-stained with PE-conjugated anti-CD21, anti-CD22, anti-CD23, or anti-CD27 mAb. (B) By comparison, cells obtained on day 6 of the 2-step culture were stained with Cy chrome-labeled anti-CD20, FITC-labeled anti-CD38, and PE-labeled anti-CD21, anti-CD22, anti-CD23, or anti-CD27 mAb. Dotted lines, isotypic control; bold lines, CD20⁻/CD38⁺⁺ cells; solid lines, CD20⁺/CD38^+/− cells. (C) Expression of CD138 was evaluated using PE-conjugated anti-CD138 mAb on CD20⁻/CD38⁺⁺ and CD20⁺/CD38^+/− cells.