Two-color staining using immunohistochemistry and TUNNEL assay, after coculture of T cells with dendritic cell-like leukemic cells from acute leukemia patients, reveals that the apoptosis of T cells is observed (brown) around leukemic cells (red) expressing the CD86 (b), CD40 (c), and FasL (d) after the formation of T cell/leukemic cell-clusters. See Fujii et al., pages 82-90.