Figure 4: The elevated P. falciparum infection supported by young RBCs is reversed as young RBCs are replaced with old RBCs. | Nature Communications

Figure 4: The elevated P. falciparum infection supported by young RBCs is reversed as young RBCs are replaced with old RBCs.

From: Host iron status and iron supplementation mediate susceptibility to erythrocytic stage Plasmodium falciparum

Figure 4

(a) Percent P. falciparum (strain 3D7) infection of RBCs of increasing diameter. Data points represent the % pRBCs of five gated RBC populations of increasing volume. Error bars represent the s.d. (b) Direct comparison of P. falciparum (strain FCR3-FMG) invasion into RBCs of increasing age. IR RBCs were separated into five fractions of increasing density, a proxy for increasing RBC age (Supplementary Fig. 3a–d). The markers represent the SI point estimate and the bar represents the 95% CI. (c) Growth rate of P. falciparum (strain FCR3-FMG) in RBC populations in which young IR RBCs were replaced with old IR RBCs (0%, 10%, 20%, 33%, 50%, 66%, 80%, 90% and 100% replacement young RBCs with old RBCs). Elongated triangles represent the percentage of young IR RBCs (gray triangle) and old IR RBCs (white triangle) in the total RBC population. Bars represent parasite growth rates after 96 h Error bars represent the s.d. *P<0.004 and **P<0.0003, compared to growth rate in 100% total IR and 100% young RBCs respectively. (d and e) Invasion into RBC populations in which young IR RBCs were replaced with old IR RBCs. Differentially labelled young and old RBCs were inoculated individually or together in the same wells at different ratios (0%, 10%, 20%, 33%, 50%, 66%, 80%, 90% and 100% replacement young RBCs with old RBCs). (d) Bars represent invasion rates. Elongated triangles represent the percentage of young IR RBCs (gray triangle) and old IR RBCs (white triangle) in the total RBC population. Error bars represent the s.d. *P<0.05 and **P<0.003 (e) Number of invasions events into young (circles) and old (triangles) RBCs as the frequency of each increases. Linear regression was used to determine best fit lines. A linear function best fit old RBC data (R2=0.9788) and a logarithmic function best fit young RBC data (R2=0.9786). Analysis of covariance was performed to determine whether invasion data of old and young RBCs differed significantly, P<0.0001. The null hypothesis was no difference between the two RBC types (H0: βIron replete=βIron deficient, α=0.05) n.s., nonsignificant.

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