Conversion of SNS in the murine CD20 sequence to ANP recovers binding of B1.

(A) The extracellular region of human CD20 was replaced with that from the murine sequence to generate the h/m chimera. Residues in the murine sequence were then mutated to produce constructs A through D. Mutated residues in constructs A through D are highlighted in bold. (B) Wild-type human CD20 (WT), h/m CD20, and constructs A through D were expressed in HEK293 cells and CD20 expression assessed by immunoblot analysis as in Figure 1. (C) Binding of anti-CD20 mAbs 1F5, 2H7, and B1 to transfected cells was monitored by flow cytometry (top); mean fluorescence values, with the isotype control values subtracted, are shown in the bar graph below. Results are representative of 4 independent experiments.