Effects of anti-CD19-Fab-SEAm against 2 CD19⁺ lymphoma cell line targets. T-cell targeting to (A) Raji cells (CD19⁺HLA-DR⁺⁺) and (B) RJ225 cells (CD19⁺HLA-DR^low) mediated by anti-CD19-Fab-SEAm fusion protein, native SEA, or C215-Fab-SEAm control fusion protein. Each value is the mean of triplicate samples. The E:T ratio was 40:1, and specific cytotoxicity was measured in a ⁵¹Cr-release assay.