Effect of Denileukin Diftitox on Immune System in CTCL Patients

This is a blood and tissue study to determine the effect of the drug called denileukin diftitox on the immune system cells that may be involved in patient response to their cutaneous t-cell lymphoma. Patients who are undergoing standard of care therapy with denileukin diftitox will be invited to participate. Blood and tissue samples will be obtained at baseline, day 5 and day 19 in up to the first 4 cycles of denileukin diftitox.