Table 3

Effect of Treatments on the Acquisition of [3H-CO]-LDL by Intracellular T. gondii

[3H-C] associated with parasites
Control100
Blockade of LDL receptors
Anti–LDL receptor antibodies10 ± 4
Defective lysosomal function
Chloroquine10 ± 6
Sucrose17 ± 7
Lysosomal cholesterol sequestration
U18666A28 ± 11
Progesterone23 ± 8
U18666A + progesterone15 ± 7
Cytoskeletal disorganization
Cytochalasin B101 ± 21
Colchicine99 ± 8
Disruption of the Golgi
Brefeldin A93 ± 7
  • [3H-C] uptake by intracellular parasites was determined 24 h after infection using 5 mg/ml [3H-CO]-LDL for 1 h. This LDL pulse-labeling followed inhibitor treatment of the infected monolayers, except for cytoskeleton inhibitor conditions, where a 10-min pulse preceded the drug incubation. Infected cells were washed after each treatment (except for lysosomal function inhibition and Golgi disruption) before purification of parasites and the determination of the levels of [3H-C] in the parasite sterol fraction. Data are expressed in percent relative to control (infected cells without treatment), taken as 100% ± SD from three separate experiments done in duplicate. The specific inhibitor treatments used were: 400 μg/ml anti–LDL receptor antibodies for 1 h at 37°C, for 30 min at 4°C; 300 μm chloroquine for 15 min; 20 mg/ml sucrose for 2 h; 1 μg/ml U18666A for 90 min; 10 μg/ml progesterone for 24 h; 50 μm cytochalasin B for 30 min; 50 μm colchicine for 30 min; 1 μg/ml Brefeldin A for 90 min.