Proliferative responses of separated T‐cell populations to stimulation with parent and hybrid cells. (a) Proliferative responses of peripheral blood mononuclear cells (PBMCs), separated CD3+ T cells, separated CD4+ T cells, and separated CD8+ T cells from Responder 2, a normal, allogeneic, Epstein–Barr virus (EBV)‐seronegative donor, to stimulation with 3·3×104 mitomycin C‐treated parent EBV B‐lymphoblastoid cell line (B‐LCL) (HMy2) cells, parent tumour cells (HL60), or HMy2×HL60 A1 hybrid cells, in mixed lymphocyte/tumour cell microcultures (MLTC) in vitro. (b) Proliferative responses of PBMCs, separated CD3+ T cells, separated CD45RO+ T cells and separated CD45RA+ T cells from Responder 3, a normal, allogeneic, EBV‐seronegative donor, to stimulation with 3·3×104 mitomycin C‐treated parent EBV B‐LCL (HMy2) cells, parent tumour cells (HL60), or HMy2×HL60 A1 hybrid cells, in MLTC in vitro.