Figure 5. Distribution of I-A^d/LACK complexes in intracellular DC compartments.

Ultrathin cryosections of DCs purified from 4 wk-infected BALB/c mice were analyzed by immunogold electron microscopy after staining with either 2C44 (A, B), anti-I-A/I-E (C), a combination of a anti-LAMP-1 mAb (10 nm gold particles) and 2C44 (15 nm gold particles) (D), or a control isotypic mAb (E). (A) Data show different magnification views of a typical micrograph showing a DC harboring one single phagosome following staining with 2C44. Upper left panel: a low magnification view showing dendrites, the nucleus and an amastigote-containing phagosome. Lower left panel: a high magnification view showing the phagosome. Upper right panel: a high magnification view (after a 90° left rotation) showing gold grains located either on the cytoplasmic membrane or on small vesicles. Lower right panel: a high magnification view showing the two double sheets of the phagosome membrane with an intense 2C44 labelling of the inner side of the phagosomal membrane. (B) High magnification view showing of a small vesicle exhibiting gold grains both on peripheral and internal membranes. (C) An amastigote-containing phagosome stained with an anti-I-A/I-E mAb showing an intense labelling of the phagosomal membrane, small vesicles and the cytoplasmic membrane. (D) A fragment of an amastigote-containing phagosomal membrane labelled with both 2C44 (white arrowheads) and an anti-LAMP-1 mAb (black arrowheads). (E) An amastigote-containing phagosome stained with a control isotypic mAb. The red and black arrows point to the phagosome membrane and dendrites respectively. N: phagosome nucleus; EC: extracellular compartment; V: vesicles.