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. 2011 Jan 31;6(1):e16414. doi: 10.1371/journal.pone.0016414

Figure 9. Phagocytosis of R29 infected erythrocytes after opsonization with anti-PfEMP1 antibodies.

Figure 9

Ethidium bromide stained R29-infected erythrocytes were opsonized with antibodies and incubated with the monocytic Thp-1 cell line. The percentage of Thp-1 cells that had phagocytosed one or more infected erythrocytes was assessed by flow cytometry. The positive control was 90 µg/ml rabbit-anti human erythrocyte polyclonal antibody and the negative control was media alone (no serum control). All antibodies to PfEMP1 domains were used at four different concentrations: 100 µg/ml (A), 25 µg/ml (B), 6.25 µg/ml (C) or 1.56 µg/ml (D). Antibodies directed against ITvar9 PfEMP1 domains (first seven bars of each graph) promoted phagocytosis of R29 infected erythrocytes, whereas antibodies to the NTS-DBL1α domains of other PfEMP1 variants (control PAR+, TM284, TM180 and HB3R+) did not. The effect of ITvar9 PfEMP1 antibodies was concentration-dependent, with anti-NTS-DBL1α being the most effective at low concentration (D). Values shown are means and standard deviation from duplicates.