Actin cytoskeleton organization in immature and mature DCs. Immature (A-B) and 24-hour, LPS-activated (C-D) D1 cells were double stained for (A,C) MARCO (red) and (B,D) filamentous actin (green) and analyzed using a fluorescence microscope. Only nonactivated cells showed organized actin cytoskeleton with visible actin cables, while mature cells showed actin with a punctate distribution. (E) MARCO expression on LPS-activated, fresh spleen-derived DCs. Fresh spleen DCs were activated with LPS and double stained with anti-B7.2 and anti-MARCO antibodies; only activated B7.2-positive DCs were also MARCO positive. (F-G) Double staining of fresh LPS-activated splenic DCs for MARCO (red) and filamentous actin (green). MARCO-positive cells showed an actin cytoskeleton with a punctate distribution. Original magnification, × 600.