Breakdown in membrane asymmetry regulation leads to monocyte recognition of P. falciparum-infected red blood cells
Fig 5
Phagocytosis of FITC-stained RBCs by primary CD14+ monocytes.
(A) Phagocytosis of uRBCs and iRBCs parasitised by P. falciparum 3D7 wildtype, CS2 wildtype, and skeletal-binding protein knock-out (CS2ΔSBP1) parasite strains. Shown is the mean percentage (± S.D.) of CD14+ (PerCP) monocytes with at least one phagocytosed FITC-stained RBC. NS = not significant; ** = p < 0.01; *** = p < 0.001 (ANOVA). n ≥ 3 independent experiments for uRBC, 3D7 iRBC, and CS2ΔSBP1 iRBC; n = 2 independent experiments for CS2 wildtype iRBC (B) Representative monocyte from (A) with a phagocytosed 3D7 iRBC. FITC fluorescence was detected at 475 nm (ex)/ 525 nm (em), PerCP fluorescence (anti-CD14) was detected at 475 nm (ex)/ 679 nm (em), and Hoechst fluorescence (DNA) was detected at 390 nm (ex)/ 435 nm (em). Scale bar = 6 μm. (C) Phagocytosis of uRBCs and 3D7 iRBCs, with and without 0.5 mM vanadate treatment to inhibit ATP hydrolysis, or 5 μg/mL Annexin V to block exposed PS. NS = not significant; * = p < 0.05; ** = p < 0.01; *** = p < 0.001 (ANOVA). n ⩾ 3 independent experiments.