T-cell plus SAg killing of malignant B cells from 12 patients with B-NHL. Target cell viability was determined by FACS analysis after a 4-hour incubation with anti-CD19-Fab-SEAm plus T cells. SAg concentration was 0.5 ng/mL, and results are shown as % dead cells after incubation with anti-CD19-Fab-SEAm minus % dead cells after incubation with the C215-Fab-SEAm control fusion protein.