Mer/Fc inhibits apoptotic cell engulfment. (A) Fluorescence analysis of phalloidin-stained J774 cells (green) engulfing Cy3-labeled apoptotic Jurkat T cells (red) in the absence (top) or presence (bottom) of 50 nM Mer/Fc. DNA is stained with Hoechst and appears blue. Bar represents 10 μm. (B) In vitro engulfment assay using J774 macrophages incubated with apoptotic Jurkat T cells in the absence or presence of increasing doses of Mer/Fc protein (n = 3) or (C) Mer/Fc plus 10 nM rhGas6 (n = 2). (D) Engulfment by cells incubated with Mer/Fc or Ret/Fc control. Results are expressed as percent of untreated control and reflect the phagocytic index of the samples assayed. The phagocytic indices of untreated controls never fell below 25.5. *P < .001.