Binding and killing with ofatumumab vs rituximab. T cells well transduced to express Q8, RQR8, or codon-optimized CD20, all coexpressed with eGFP. (A) T cells were stained with either rituximab or ofatumumab and a secondary anti-human-Fc allophycocyanin-conjugated goat antibody. Antibody binding vs eGFP expression is shown. Q8 binds neither mAb; CD20 binds both, whereas RQR8 only binds rituximab. (B) Next, primary human T cells were transduced with these constructs and a CDC assay was performed with either rituximab or ofatumumab. The percentage lysis as determined by Annexin-V and PI positivity is shown. Q8 transduced to T cells was not lysed by either mAb; T cells expressing CD20 were lysed by both, whereas RQR8 T cells were lysed only by rituximab. This experiment was performed in 1 donor.