CD28 and acute lymphoblastic leukemia: Compared with the saline-treated group (control), mice treated with low-dose (LD) and high-dose (HD) hCD28-mAb, rhCD40 or both displayed enlarged spleens (Fig. 7F); the infiltrated T-ALL cells in the spleens and BMs were also dramatically increased upon activation of CD28- and/or CD40LG-signaling (Fig. 7G).