CD126 up-regulation is specific for plasmablasts and not dependent on cytokine combination.

(A) From days −4 to 0, IL-2R and IL-6R expression was determined in simple-staining. From days 2-7, IL-2R and IL-6R expression was determined in double-staining with anti-CD20–FITC and anti-CD25–PE mAbs or anti-CD20–FITC and anti-CD126–PE or anti-CD20–FITC and anti-CD130–PE mAbs, respectively, and only the phenotype of the CD20⁻ population (the differentiated population) was reported. Results are expressed as the intensity fluorescence ratio mean ± SD of 4 experiments. (B) Activated memory B cells (day 0) were cultured for 2 days in the presence of (1) 50 U/mL IL-2 or (2) 100 ng/mL IL-10 or (3) IL-2 + IL-10 or (4) IL-2 + 10 ng/mL IL-6. CD126 expression was determined as described in Figure 3. Results show 2 representative experiments out of 3.