FIG 2.

FCR3-CSA IgG1 recognition by Malian women correlates with DBL3χ and DBL5ε ELISA reactivity. (A) Uninfected erythrocytes and magnetically enriched P. falciparum 3D7, FCR3, and FCR3-CSA IEs were incubated with purified IgGs from rabbits immunized with DBL3χ or adjuvant alone. Cells were then incubated with Alexa Fluor 488-conjugated goat anti-rabbit IgG for fluorescence detection (x axis). Each experiment was performed at least twice, with >50,000 IE events collected per experiment. Representative histograms are shown. (B) Human IgG subclass binding to FCR3-CSA late-stage IEs was detected by flow cytometry using mouse anti-human IgG subclass-specific antibodies and Alexa Fluor 647-conjugated goat anti-mouse antibodies. At least 5,000 IE events were analyzed for median fluorescence intensity (MFI). Bars show the means of duplicates. Malian women showed significantly higher IgG1 binding than Malian men (P = 0.0002). (C) For Malian women, IgG1 binding to FCR3-CSA IEs is shown in relation to IgG recognition of DBL3χ and DBL5ε by ELISA. The P value and Spearman's r coefficient are reported for each antigen.