Successful murine tumor allotransplantation after total lymphoid irradiation

C3H/Km (H-2k) mice were treated with fractionated total lymphoid irradiation (TLI) (17 x 200 rad) and then were inoculated with 3 x 10(6) tumor cells from the EMT6 tumor cell line derived from the BALB/c (H-2d) mouse. One group of mice also received an i.v. infusion of BALB/c bone marrow (3 x 10(7) cells). Tumors in control animals (no TLI) became palpable within 10 days after inoculation, but subsequent tumor regression was rapid, with complete disappearance in all animals by 23 days. Initial tumor growth was exponential in both groups of mice treated with TLI, but tumors regressed after 30 days in the animals treated with TLI alone. In the group treated with TLI and bone marrow infusion exponential tumor growth continued until pulmonary metastases developed and all animals died. The TLI-treated mouse provides a model for tumor allografting. Further development of this model may demonstrate its efficacy in human tumor xenotransplantation.