The statistically significant increase in survival of the group given 10 × 106Itk–/– donor T cells compared to the group given 1 × 106 WT donor T cells suggests that the increase in survival from GVHD is preserved even when transplanting the maximum number of T cells from mice lacking ITK compared with T cells from WT mice (Figure 1B). Here, ITK is linked to graft versus host disease.