Figure 4.

C3d inhibits the proliferation of BCR activated human B cells. Resting human B cells were cultured with complexes consisting of either streptavidin-conjugated biotinylated anti-IgG/A/M (control) or streptavidin-linked biotinylated anti-IgG/A/M and biotinylated C3d in different concentrations as indicated. Cells were pulsed with 1 μCi/sample [³H]-thymidine after 48 h and harvested 20 h later. Mean counts per minute (cpm) values ± SD of triplicate samples of a representative donor are shown (A). The relative mean effect of C3d on proliferation ± SD in samples stimulated with BCR were calculated from three independent experiments (B). *p < 0.05, **p < 0.01, ****p < 0.0001.