In the mixture experiment (Figure 3 ), we used non-AMA1 IgGs at 4 mg/ml, while the physiological concentration of IgG in human serum is 10-20 mg/ml. In the previous study where we prepared non-AMA1 IgGs from Malian adults, 4 and 0.4 mg/ml of non-AMA1 IgGs were tested. However, 0.4 mg/ml of non-AMA1 IgGs did not show a clear interference effect [27] . The result suggests that a certain level of non-AMA1 IgGs is needed to detect interference effect in this assay. On the other hand, if we use non-AMA1 IgGs at 10 or 20 mg/ml, several of them show .20% inhibition by themselves (Figure 2 ), so that it is difficult to calculate the interference effect, as the mixture cannot show lower inhibition than non-AMA1 IgG alone. Therefore, we decided to use the same 4 mg/ml concentration as the previous study [27] . The concentration of AMA1-specific IgG in the US-total IgG used for the mixture experiment was at 133 (for 3D7 parasites) or 202 (for FVO) mg/ml, and median level of AMA1-specific antibody in Malian children after immunization was 111.6 mg/ml [28] . Therefore, it is reasonable to assume than non-AMA1 IgGs interfere with growth-inhibitory activity of AMA1-specific IgG at physiological ratio (i.e., mix 10-20 mg/ml of non-AMA1 IgGs with 100 mg/ml AMA1-specific IgG).