Clustering of BCR and DC-SIGN in FL B cells. Sorted CD44⁻IgD⁻ GC B cells and purified IgM⁺ FL B cells were incubated with unlabeled rhDC-SIGN before incubation on fibronectin-coated glass and fixation. DC-SIGN was revealed using mouse IgG2b anti-human DC-SIGN primary mAb and A488-donkey anti-mouse IgG2b secondary Ab whereas IgM⁺ cells were directly stained using A549-goat anti-IgM Ab. One example highlighting DC-SIGN/BCR colocalization is shown in panel A. Scale bar, 2.5 µM. The DC-SIGN:IgM rMFI was obtained for 100 cells per sample in 3 pooled GC B-cell samples, 6 IgM⁺ Lo-B FL samples (FL1, FL6-10), and 4 IgM⁺ Hi-B FL samples (FL3, FL5, FL11, FL12) (B). The Kruskal-Wallis nonparametric test followed by the Dunn posttest was used to compare FL samples with GC-M samples; ***P < .0001.