CD138⁺HLA-DR⁺ plasmablasts (PB) cells are recently differentiated IgG-producing PB.

<div><p>(A) The effects of influenza vaccination on the frequencies of B-cell subpopulations were analyzed. The frequency of each B-cell subpopulation derived from the peripheral blood of healthy subjects before (pre) and seven days after vaccination (post) is shown. Each line connects the values obtained from a single subject (*p < 0.05 by Wilcoxon signed rank test). </p> <p>(B) The results of intracellular IgG staining of HLA-DR⁺ PB (left) and HLA-DR^- PBs (right) are shown. The values represent the percentages of IgG-producing cells in each PB subpopulation. Representative data of one out of three individuals are displayed.</p>