CTL-mediated cytolysis of lymphoma cells. Eight HLA-A2–positive lymphoma cell lines were loaded with influenza peptide (♦) or HIV peptide as negative control (⋄) and coincubated for 4 hours with an influenza-peptide–specific T-cell line. The ninth cell line, K 562 A2, is a myeloid cell line and was used as a positive control. Specific cytolysis was determined by propidium iodide assay. Means and SEM of 3 experiments are shown.