FIG 5.

Functional disruption of CD47-SIRPα interactions with human SIRPα-Fc proteins and anti-SIRPα antibodies increases phagocytosis of P. falciparum-infected RBCs by human macrophages not LPS or IFN-γ prestimulated. Shown are human SIRPα-Fc recombinant protein treatment (white boxes) or control IgG4-Fc treatment (gray boxes) (A) and anti-SIRPα antibody treatment (white boxes) or control IgG1 treatment (gray boxes) (B) of uninfected RBCs and P. falciparum-infected RBCs at ring stage (left) and mature stage (right) incubated with human monocyte-derived macrophages. Comparisons of phagocytic indexes in control IgG4-Fc- versus SIRPα-Fc-treated macrophages (A) (*, P = 0.026; Mann-Whitney test) or control IgG1- versus anti-SIRPα antibody-treated macrophages (B) (*, P = 0.019; Mann-Whitney test) for ring-stage P. falciparum-infected-RBC phagocytosis are shown. The results are the combined data from three experiments and are shown as box-and-whisker plots, representing interquartile and complete ranges, with the horizontal line in each box indicating the median level of phagocytic index. ns, not significant.