Efficient harvest of in vivo IL-2-activated CD3+ lymphocytes for adoptive immunotherapy by selective leukapheresis (lymphocytapheresis).

Autologous activated lymphocytes are an alternative to tumor-infiltrating lymphocytes for adoptive immunotherapy. We developed a method of selective lymphocytapheresis that harvests large numbers of interleukin-2 (IL-2)-activated autologous T lymphocytes. Five patients with metastatic malignant melanoma received 2.4 x 10(6) IU/m2 IL-2 sc. once a day 5 days a week for 3 weeks before lymphocytapheresis. Four patients went through lymphocytapheresis without IL-2 pretreatment. After IL-2 pretreatment, activated memory T cells increased significantly. Increasing CD3+ cells paralleled the significant enhancement of the cytotoxic activity against an HLA-A2-matched allogeneic melanoma cell line during the 3 weeks of IL-2 pretreatment. Lymphocytapheresis was performed 72 h after the last IL-2 injection to obtain the maximum recovery of activated lymphocytes at the peak of the rebound phenomenon. IL-2 pretreatment resulted in many more lymphocytes in the harvest than without pretreatment. The percentage, number, and lytic units of CD3+ cells harvested by the differential apheresis were significantly higher than were present in peripheral blood before lymphocytapheresis. These results show that pretreatment of melanoma patients with low-dose IL-2 before lymphocytapheresis allows the selective harvest of large numbers of activated T lymphocytes for adoptive immunotherapy.