Induction of BCR signaling by DC-SIGN in FL B cells. (A) Purified Hi-B FL B cells were incubated with mouse IgG1 anti-human CD19 mAb alone (Ctrl) or before stimulation with mouse IgG3 anti-IgM mAb (αIgM) or rhDC-SIGN. After fixation, cells were stained with A594-goat anti-mouse IgG1 Ab, A647 goat anti-human IgM Ab, and, when appropriate, mouse IgG2b anti-DC-SIGN primary mAb and A488-donkey anti-mouse IgG2b secondary Ab. Shown is 1 experiment representative of 3. Scale bar, 2.5 µM. (B) Purified B cells from Lo-B FL and Hi-B FL samples were stimulated for the indicated time points with uncoated Dynabeads (Ctrl), mouse IgG3 anti-IgM mAb (BCR), or Dynabeads coated by rhDC-SIGN (DC-SIGN). Western blot revealed pSYK, pAKT, and pERK and were normalized using anti-β-actin. Shown is 1 experiment representative of 3.