Fig. 2. Phase-contrast and fluorescence microscopy of IgG-Es and F-actin during phagocytosis in macrophages treated with 0.1% dimethyl sulfoxide (control), 100 nM wortmannin or 10 µM ML-7. Macrophages were pretreated with one of the drugs for 15 minutes, fed IgG-Es and incubated for 30 minutes in the presence of the drug. After fixation, extracellularly exposed IgG-Es and F-actin were stained with FITC—anti-rabbit-IgG and rhodamine phalloidin, respectively. In control cells (A-C), IgG-Es were internalized in phagosomes and/or phagolysosomes, and were scarcely associated with F-actin. In wortmannin-treated cells (D-F), IgG-Es seemed to be surrounded by F-actin-rich protrusions but remained partially exposed to extracellular fluid. ML-7-treated macrophages (G-I) appeared similar to wortmannin-treated cells. (A,D,G) Phase-contrast images. (D,E,H) FITC images showing extracellular IgG-Es. (C,F,I) Rhodamine images showing F-actin. Bars, 10 µm.