Fig. 4.

CD23 expressing cells preferentially bind α2,6-sialylated IgG. (A) In cell-based ELISA binding assays, DC-SIGN, CD23, and/or mock transfected CHO-K1 cells were pulsed with an increasing amount of sialylated (sIgG) or asialylated IgG. (A and B) For competition binding assays, DC-SIGN–expressing cells (B) or CD23-expressing cells (C) were pulsed with a constant amount of sIgG and an increasing amount of soluble CD23 or DC-SIGN. In all panels, bound IgG was detected using HRP-labeled anti-human antibody. ECD, extracellular domain.