Figure 1

Isolation of Plasmodium falciparum trophozoites by flow cytometry. On the left panel, Figures 1a, 1b, and 1c represent a two-dimensional scattergram which corresponds to low-angle light scatter (FSC-A) as a function of fluorescence intensity (PhycoErythrine, PE-H). On the right panel, Figures 1d, 1e and 1f represent the number of trophozoites detected (counts) as a function of fluorescence intensity (PE-A). Logarithmic red fluorescence was detected through a 585/42 nm band pass filter (FL2). The speed of sorting corresponded to 5,000 events/sec and for each sample, 50,000 cells were acquired, stored and analysed. Note that the scales of these figures are not the same. P1 window (blue) represents the trophozoite population (the negative control contains debris). P2 window (pink) indicates the position of white blood cells. Figure 1a shows an uninfected blood sample used as a negative control. The corresponding histogram (Figure 1d) shows the distribution of debris. In the middle panel (Figure 1b) the scattergram of the population of parasite stages found in a P. falciparum 3D7 culture is shown (Figure 1b). The corresponding histogram (Figure 1e) shows the distribution of trophozoites in the P1 zone. The lower panels (Figure 1c and Figure 1f) represent the parasitaemia of an infected field sample (patient 2 – Table 1).