SRL but not TAC inhibited the proliferation of CD19⁺CD27⁻ naïve and CD19⁺CD27⁺ memory B cells.

<p>B cells were purified by depleting non-B cells resulting in >95% CD19⁺ cells which subsequently sorted into CD27⁻ (naïve) and CD27⁺ (memory) B-cell fractions. These subsets were labeled with CFSE, stimulated with anti-IgM, anti-CD40 mAb and IL-21 in the absence (CTRL) or presence of TAC or SRL at 6ng/ml and were analyzed by multicolor flow cytometry after 6 days in culture. <b>(A)</b> A representative experiment: histogram plots show dilution of CFSE in the proliferating CD19⁺CD27⁻ (upper panel) or CD19⁺CD27⁺ (lower panel) cells. <b>(B)</b> Data are from four different independent experiments are shown as mean ± SD percent proliferating naïve CD19⁺CD27⁻ and memory CD19⁺CD27⁺ B cells. <b>(C)</b> B cell subsets showing indicated surface markers were analyzed and plotted as mean ± SD (n = 4) percent of proliferating cells in the cultures of naïve CD19⁺CD27⁻ (upper panel) and memory CD19⁺CD27⁺ B cells (lower panel). The residual cells that proliferated in presence of SRL demonstrated an activated phenotype. *p < 0.05, **p < 0.01.