Figure 1.

FACS analysis of A₂ RBC converted from A₂B cells. The FACS histograms show the B antigen site density as measured by anti-B fluorescein isothiocyanate-labelled monoclonal antibody on A₂B (A), native (B) and enzymatically converted A₂ RBC (C). The x-axis represents the fluorescence intensity on a logarithmic scale, whereas the y-axis shows the number of RBC evaluated. The antibody diluting concentration was 1:128. The native A₂B showed a higher positive rate, 99.3%, but native A₂ and enzymatically converted A₂ RBC gave low positive rates of 0.3% and 0.7%, respectively.