OPN-stimulated DCs show morphologic signs of activation. DCs derived from peripheral blood monocytes were left untreated (A-C), or stimulated with 0.5 μg/mL OPN (D-F) or 10 μg/mL LPS (G-I) on day 5 of culture. Photographs of cultures were taken 24 hours (A,D,G) and 48 hours (B,E,H) after addition of the stimulus. Bar in panel A for magnification in panels A-B, D-E, G-H: 150 μM. For morphologic evaluation of DCs, cells were cultured as described in “Materials and methods,” and after 48 hours of treatment, unstimulated DCs (C), OPN-stimulated DCs (F), or LPS-stimulated DCs (I) were fixed on adhesion slides and stained immunohistochemically with antibodies against HLA-DR. Bar in panel C for magnification in panels C,F,I: 15 μM. Panels A-B, D-E, G-H: Cell cultures were analyzed with an Axiovert microscope (Zeiss, Göttingen, Germany) using a Zeiss 10.0 objective lens providing a 10-fold magnification. Panels C, F, I: Adhesion slides were analyzed with an Axioskop microscope (Zeiss) with oil immersion using a 100× objective lens (Plan Neofluar objective, Zeiss). Photos were taken with a Canon EOS 300V (Canon, Krefeld, Germany) used as an onboard camera without additional optical lenses. All slides were scanned with CanoScan (Canon), and images were assembled with CorelDraw 11.