Immunofluorescence analysis of MARCO expression on LPS-activated D1 cells. D1 cells were grown on a glass coverslip. Immature (A,C) and 24-hour LPS-activated (B,D) D1 cells were stained with DAPI (4,6 diamidino-2-phenylindole), to identify the nuclei, and with the anti-MARCO mAb (A-B) or an irrelevant control (C-D). The MARCO expression was analyzed by fluorescence microscopy. Original magnification, × 400.