Internalization of ApoS by CR3 and αvβ5. (A) ApoS were stained with PKH67 and cocultured with DCs at 37°C for 2 hours. DCs were gated by FSC/SSC and expression of MHC II and analyzed for association with PKH-labeled ApoS. Each dot represents the value for DCs of a healthy donor after the background value (association of DCs with IgG-ApoS) was subtracted (left), and the line represents the averaged value of all donors. A representative dot plot is shown on the right. (B) DCs were cocultured with CD11b-, αvβ5-, or control ApoS for 2 hours and then fixed for preparation of EM slides. The data represent an average from 3 donors tested; error bars represent SD. For each donor, DCs that contained 2 or more ApoS were counted in at least 5 EM slides at low magnification (magnification × enlargement factor was 4500 for αvβ5 and 2100 for CD11b). (C) EM photos are shown of DCs interacting with αvβ5-ApoS (left) or CD11b-ApoS (right).