Extended Data Figure 8. Comparing parasite invasion and biomechanical properties of frozen and fresh RBCs.

Comparison of parasite invasion efficiency and biomechanical properties in frozen vs fresh RBCs. (a) The invasion efficiency of P. falciparum laboratory strain, 3D7, was compared across frozen and fresh RBCs (n=6 frozen and n=14 non-Dantu, 12 Dantu heterozygote and 12 Dantu homozygote fresh biologically independent RBC samples per genotype group were tested). The percentage of parasitised RBCs that successfully invaded each genotype group was measured using a flow cytometry-based invasion assay. Boxplots indicate the median (middle line) and interquartile ranges (top and bottom of boxes) of the data, while whiskers denote the total data range. Statistical comparison across the three genotype groups was performed using a one-way ANOVA test, while pairwise comparisons between genotype groups were performed using the Tukey HSD test, with significant differences in 3D7 invasion observed in frozen RBCS (non-Dantu vs. Dantu homozygote p=0.001) and in fresh RBCs (non-Dantu vs. Dantu homozygote p=0.001). **p < 0.01; *p < 0.05. (b) Membrane flickering spectrometry enabled measurement of RBC biomechanical properties (bending modulus, tension, radius, and viscosity) of fresh (n = 53) and frozen (n = 51) RBCs from the same donor. No statistically significant differences were detected between the two conditions for all the measured biophysical properties. Pairwise comparisons were performed using the two-sided Mann-Whitney U test; p Bending modulus = 0.1, p Tension = 0.6, p Radius = 0.7, p Viscosity = 0.6.