CD4+ T cells tumor specific response exists in L615 leukemia mice: adoptive transfer in combination with cyclophosphamide.

Aim: L615 leukemia cell line is a transplantable acute lymphocytic leukemia model with the CD4 positive phenotype. In this study, we explored whether tumor response specific T cells can be separated from the live leukemia mice or not. Methods: The mutant HGPRT- L615 cell line was first established. The splenocytes from HGPRT-L615 leukemia mice were cultured and expanded in mixed tumor-lymphocytes culture manner. The expanded T cells were sorted with FACScan. Then their killing capacity, IFN-gamma release as well as antitumor capacity in adoptive transfer experiments were analyzed. Results: The expanded response T cells are mostly CD4 positive. The CD4 positive T cells showed high release of IFN-gamma upon stimulation but lacked significant cytotoxicity. In immunochemotherapy model, these CD4 positive T cells can cure most leukemia mice. Conclusions: We demonstrated the feasibility of separation of tumor response specific CD4+ T cells from CD4+ L615 leukemia mice. These CD4+ T cells can cure leukemia mice upon adoptive transfer in combination with cyclophosphamide pretreatment.