Localization of liposomes and
S aureus in granulocytes by confocal laser microscopy and electron microscopy. (A) Confocal laser microscopy. Granulocytes (1 × 106/mL) were incubated at 37°C for 15 minutes with 10 × 106 BODIPY-labeled (green) S aureus particles, followed by an incubation with 1 mM rhodamine-B-PE–labeled (red) liposomes (EPC:EPG:Chol, 4:3:3 mole ratio) for 20 minutes. Colocalization of S aureusand liposomes is suggested in several vacuoles appearing yellow (red-green overlay). (B) Confocal laser microscopy. Same granulocyte visualized by differential interference contrast (DIC) microscopy. (C) Electron microscopy. Isolated normal granulocytes (15 × 106/mL) were incubated with 15 × 107S aureus particles and 3 mM ferritin-containing liposomes (EPC:EPG:Chol, 4:3:3 mole ratio) at 37°C for 60 minutes. The arrow indicates the ferritin particles derived from liposomes. (D) Higher magnification of the ferritin-containing vacuole of the same cell as in panel C.
