CD4 and graft versus host disease: We found that in the GvHD group, 14, 21 days after transplantation, CD4+ T cells had higher FasL expression than that in the BMT group (72.8±6.24% vs 45.72±2.53%, at day 14, P = 0.0002, and 72.2±8.61% vs 31.35±7.84% at day 21, P = 0.0004, n = 4, respectively, Figure 6I&J).