To learn more about the way the EBV-CTLS are working and how long they last in the body, 10-60 mls of blood will be taken before and after each infusion. Up to 60 ml of blood will also be drawn before each cycle of chemotherapy that occurs at Week 1, Week 4, Week 7, Week 10 before the T cell infusion and then at Weeks 1, 2, 4, 6 and 8 weeks after infusion, and then again at the follow-up visits 5, 8, and 11-12 months after infusion. This blood will be used to look at the immune response to the patient's cancer. If the patient only has one EBV-CTL infusion, up to 108 teaspoons of blood will be drawn to allow for evaluation of his or her response to treatment; however, the total amount of blood collected on this study will depend on the total number of EBV-CTL infusions that the patient has.