Target cell specificity of leukemia reactive T cells generated by CD80-transfected AML cells. (A) Leukemic-cell reactivity of two T-cell lines generated against CD80-transfected AML cells. T-cell lines were tested against untransfected AML cells and patients’ EBV-LCL after second stimulation. (B) Proliferative activity of oligoclonal T-cell cultures (semiclones) generated from T-cell line #1. The results are expressed as the mean cpm of triplicate cultures. The SEM did not exceed 15%. (C) Preferential recognition of leukemic cells by four T-cell clones generated from a type II semiclone shown in Fig3B.