CD4 and acute lymphoblastic leukemia: The seventh group of recipient BALB/c mice was transplanted with 10 × 106 1bone marrow cells, and recipient mice were also given 2.5 × 106 CD4+ and 2.5 × 106 CD8+ T cells from Itk–/− mice and challenged with 2 × 105 luciferase‐expressing B‐ALL tumour cells (group 7).