Surface phenotype of CpG DNA₂₀₀₆ activated CD27⁺ and CD27⁻ B cells with CD138 induction. Surface phenotype of the CD27⁺ and CD27⁻ peripheral blood B cells beginning with the initial isolation and following each culture phase. Both CD27⁺ and CD27⁻ B cells were activated by CpG DNA and underwent plasmablast differentiation, ultimately resulting in a surface phenotype characteristic of human bone marrow–resident plasma cells: CD20⁻, CD38⁺⁺⁺, CD138⁺⁺, and HLA-DR⁻. Results are representative of 15 independent experiments from 12 different blood donors.