To observe the effect of Ly49A transfected mouse spleen cells on graft versus host disease (GVHD) and graft versus leukemia (GVL) effect after haploidentical allogeneic bone marrow transplantation in mice. Ly49A gene was transfected into spleen cells of C57BL/6 mice by retrovirus and the expression rate of Ly49A receptor was evaluated by flow cytometry. The murine model of haploidentical allogeneic acute GVHD was established by using C57BL/6(H - 2b) mouse as donor, and (BALB/c x C57BL/6) F1(H - 2d/b) (CB(6)F(1)) mouse as the recipient which was injected EL9611 cells before transplantation. After irradiation (TBI, (60)Co 10.5 Gy), the recipient received mixed graft of spleen cells and bone marrow cells to establish a GVHD model. The effects of Ly49A transfected spleen cells on GVHD and GVL post haploidentical allogeneic bone marrow transplantation were detected with this model. The expression rate of Ly49A receptor was (42.20 +/- 4.87)%, (18.67 +/- 2.48)% and (18.73 +/- 3.82)% for pLXSN-Ly49A, pLXSN transfecte