Figure 3.

Induction of cytotoxic T‐lymphocyte (CTL) activity. Separated T cells from Responder 1, a normal, Epstein–Barr virus (EBV)‐seronegative donor, were cultured in vitro with mitomycin C‐treated HMy2, HL60, or HMy2×HL60 A1 hybrid cells, restimulated after 7 days (in the presence of interleukin‐2, 20 U/ml), and CTL activity was determined against target cells HMy2, HL60, HMy2×HL60 A1, and the unrelated tumour cell line, CEM, on day 14 by ⁵¹Cr‐release assays. Each parent cell line stimulated activity against itself, but not against the other parent cell or against CEM, whereas HMy2×HL60 A1 hybrid cells stimulated CTL activity against both parent cell lines and itself, but not against CEM targets. Natural killer (NK)‐cell activity is shown using the NK‐sensitive K562 cell line as target cells.