FIG 4.

P. falciparum-iRBC lysates do not induce apoptosis in HBMECs. HBMEC monolayers were incubated with increasing concentrations of (A) TNF-α or (B) RBCLs and iRBCLs (8 × 10⁶/cm²) for the indicated times. (A and B) The presence of early apoptotic (annexin V⁺ PI⁻) and necrotic (annexin V⁻ PI⁺) populations was detected by flow cytometry. (C and D) HBMEC monolayers were incubated with RBCLs (8 × 10⁶/cm²), iRBCLs (8 × 10⁶/cm²), or H₂O₂ (1 mM) as a positive control and stained for F-actin (green) and PI (red) to detect necrotic cells (C) or PI and nuclear staining to quantify the number of HBMECs that remain attached to the coverslip (D) at 3 and 6 h after treatment. (C) Representative immunofluorescent images are shown. The relative frequency of PI⁺ cells (C) and the average number of nuclei per field from 3 fields (D) from 2 independent experiments are shown and include the medium control. (A and B) Results are the average from 3 independent experiments with standard deviations. Statistical significance was determined by one-way ANOVA with Tukey’s multiple-comparison test (B) or the Kruskal-Wallis test with Dunn’s multiple-comparison test (C and D) (*, P < 0.05; **, P < 0.01).