Figure 4.

Immunolocalization of tachyzoite (anti-SAG1, red) associated to host cells. (A) MLN CD11c⁺ cell (green) at 5 days after inoculation. (B) MLN MHC class II⁺ (green) cell at 5 days after inoculation. Among the parasitized cells at day 5 after inoculation, approximately 59% express MHC class II molecules, which are constitutively expressed by DCs, 20.9% express CD11b and 11.7% express CD11c (n parasites > 100 for each subset). (C-E) Confocal microscopy (0.4 μm section) in MLN cells at day 5 after inoculation. Tachyzoites (red) are surrounded by CD11b⁺ host cell plasma membrane (green) (CD) or by CD45⁺ host cell plasma membrane (green). (F) Single tachyzoite (red) is associated with a blood CD11b⁺ host cell (green) at day 7 after inoculation. Nuclei were stained with DAPI (blue). Scale bar = 2 μm. Images were visualized with a 63×/1.25 Plan-neofluar objective lens (Zeiss, Le Pecq, France).