Characteristics of antibodies promoting phagocytosis. (A) Pairwise correlation between the relative phagocytosis index and IgG ELISA optical density (OD) against whole merozoites. (B) IgG subclasses against whole merozoites measured by ELISA. (C) Pairwise correlation between the relative phagocytosis index and parasite growth inhibition measured in the GIA. (D) Pairwise correlation between IgG ELISA OD against whole merozoites and GIA. Data from GIAs (C and D) are expressed as parasite growth (%), relative to malaria-naive controls. Experiments were conducted using purified IgG from adults and children in Ngerenya , n = 33. GIA, growth inhibition assay.