Syngeneic adoptive immunotherapy and chemoimmunotherapy of a Friend leukemia: requirement for T cells.

The aim of the study was to determine which cell mediates adoptive immunotherapy and chemoimmunotherapy of a syngeneic transplantable Friend virus-induced leukemia (FBL-3). An adoptive immunotherapy model was developed in which adult C57BL/6 mice given a lethal dose (10(4)) of FBL-3 on day 0 were saved by treatment on day 1 with C57BL/6 spleen cells or peritoneal exudate cells (PEC) immune to FBL-3. Cells passed through a nylon wool column to remove B cells and macrophages or treated with carbonyl iron to remove phagocytic cells remained effective, whereas cells treated with anti-theta serum and complement were far less effective. For adoptive chemoimmunotherapy, mice inoculated with 10(7) FBL-3 were treated 5 days later with cyclophosphamide (CY) plus immune spleen cells. CY, with or without non-immune cells, prolonged survival but all mice died with leukemia, whereas mice given CY plus immune cells survived tumor-free. As an adjunct to CY, immune cells passed through nylon wool or treated with carbonyl iron remained quite effective whereas cells treated with anti-theta serum and complement were far less effective. Thus, immune thymus-derived lymphocytes were required for the adoptive immunotherapy of an early leukemia or chemoimmunotherapy of a disseminated leukemia.