Figure 2

IVIg inhibited mouse angiogenesis via its Fc fragment and FcγRI engagement. (a, b) The Fc fragment of IVIg (IVIg-Fc), but not the Fab fragment (IVIg-Fab), inhibited choroidal angiogenesis in wild-type mice and xenograft tumoral angiogenesis in nude mice, as seen in (a) quantification of choroidal angiogenesis volume (n=4–8) and tumor CD31 immunolocalization (n=7) compared with PBS group (IV PBS), and (b) representative histology images of tumor tissue (CD31+, brown). Scale bar, 100 μm. (c) IVIg-Fc, but not IVIg-Fab, suppressed xenograft tumor growth, as compared with PBS. (d) IVIg did not inhibit choroidal (n=6–8), corneal (n=8) syngeneic tumor (n=7) or muscle (n=8) angiogenesis in Fcgr1^−/− mice, which lack FcγRI. No significant difference between groups. (e), Representative histology images of syngeneic tumor tissue in Fcgr1^−/− mice (CD31+, brown) treated with either IVIg or IV PBS. Scale bar, 100 μm. (f) IVIg did not suppress tumor growth in Fcgr1^−/− mice, as compared with IV PBS. n=7. (g) IVIg did not inhibit choroidal angiogenesis in Fcer1g^−/− mice, which lack functional signaling of activating FcγRs; n=6. (h) IVIg-Fc did not inhibit choroidal angiogenesis in Fcgr1^−/− mice. n=6. Results are means±s.e.m. *P<0.05 compared with IV PBS.