FIG. 4.

Inhibition of DBPII binding to human erythrocytes. Human antibodies specific to the H1, H2, H3, L3, L4, and NI peptides were tested to determine their abilities to inhibit DBP binding to Duffy-positive erythrocytes. Different concentrations of the antibodies were preincubated with transfected COS7 cells prior to addition of erythrocytes, and the numbers of rosettes in 30 microscopic fields at a magnification of ×200 were determined. The symbols indicate the mean percentages of binding for three independent experiments compared to the results of a control experiment with no antibody, and the error bars indicate the standard deviations. For an antibody concentration of 10 μg/ml the P value was <0.0001 for comparisons of H and L peptides, H and NI peptides, and L and NI peptides. P values were adjusted for multiple comparisons.