FIG. 3.

Human plasma samples compete with processing-inhibitory MAbs for binding to MSP1₁₉. A competitive ELISA was used to determine whether or not antibodies developed during natural infection with P. falciparum could competitively block the binding of MAbs 12.8 and 12.10. The results presented are for the same plasma samples as those described in the legend to Fig. 2 and arranged in the same order: (i) labeled antibody bound in the absence of a competitor (no Ab), (ii) labeled antibody bound in the presence of a competitor MAb (12.8), and (iii) labeled antibody bound in the presence of human plasma samples as indicated (remaining samples shown, individually labeled). The binding of MAb 12.8 to antigen is expressed as a percentage of the amount bound in the absence of a competitor; similar results were obtained for biotinylated MAb 12.10 (data not shown).