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. 2009 Mar 20;284(12):7495–7504. doi: 10.1074/jbc.M808643200

FIGURE 4.

FIGURE 4.

SP-A enhanced CR3-mediated phagocytosis. The effects of SP-A and iC3b on the phagocytosis of FITC-labeled H. influenzae were determined in CHO-WT cells and CHO-CR3 cells. In the absence of opsonins, the phagocytosis of H. influenzae was greater in CHO-CR3 cells (solid bar) compared with CHO-WT cells. iC3b, a known opsonin and ligand for CR3, enhanced CR3-mediated phagocytosis of H. influenzae in cells that expressed CR3 (open bar, panel A). SP-A enhanced CR3-mediated phagocytosis in CR3 expressing cells (hatched bar, panel A). There was no additive or synergistic effect of SP-A and iC3b on phagocytosis, the combination enhanced CR3-mediated phagocytosis to a similar extent as SP-A or iC3b alone (cross-hatched bar, panel A). SP-A-mediated enhancement of phagocytosis of H. influenzae into CR3 expressing cells was reduced by pre-treatment of SP-A with collagenase (colSPA) or N-glycanase (degSPA), suggesting roles for oligomeric assembly, the collagen like domain and N-linked carbohydrate in this effect (panel B). Data are mean ± S.E. with n = 4 experiments per group, *, p < 0.05 compared with phagocytosis by CHO-CR3 cells.