Exogenous VEGF₁₆₅ inhibits HTLV-1 entry into primary DCs. (A) Cell- surface levels of HSPGs or NRP-1 on primary MDDCs and COS cells. The gray lines represent the isotype control; black lines, staining with the anti-HSPG (10E4) or anti-NRP-1 (BDCA4) mAb, as indicated. (B) Effect of exogenous VEGF₁₆₅ on the binding of the HTLV-1 SU to MDDCs. MDDCs were incubated in the presence or absence of VEGF₁₆₅ (50 ng/mL) for 30 minutes and then exposed to the HTLV-1 SU-rFc (black lines) or the control SU-ASLV-rFc (gray lines) and the level of binding determined. (C) Effect of exogenous VEGF₁₆₅ on the internalization of HTLV-1 or HIV-1 into MDDCs. MDDCs were incubated in the presence or absence of VEGF₁₆₅ (50 ng/mL) for 30 minutes and then with culture medium (gray lines) or 100 ng/mL of either HTLV-1 (top panels) or HIV-1 (bottom panels) virions (black lines). After 2 hours at 37°C, MDDCs were permeabilized, stained with an antibody directed against the viral core proteins (HTLV-1 MAp19 or HIV-1 CAp24), and virus internalization determined.