SAg-mediated T-cell killing of B-CLL target cells. Cells from 6 patients with B-CLL were cultured for 3 days with TPA (▪, ♦) or in medium alone (□, ⋄) and used as targets. Cytotoxic T cells were directed by addition of anti-CD19-Fab-SEAm fusion protein or C215-Fab-SEAm control fusion protein. Results are the mean ± SD. 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.