OBJECTIVETo study if methoxy polyethylene glycol modification (mPEG) affects grafts versus leukemia (GVL) when donor bone marrow mononuclear cells are camouflaged with mPEG in murine bone marrow transplantation (BMT).

METHODSSixty (BALB/c(H-2d) x 615(H-2k))F(1) mice were divided into four groups randomly. Mice in group A were only irradiated with 8.0 Gy (60)Cogamma, and mice in the other groups were inoculated intraperitoneally with 1 x 10(6) L615 cells 3 days before irradiation with the same dose (60)Cogamma. BALB/c(H-2d) mice were sacrificed and bone marrow cells and spleen cells were collected. The bone marrow cells (1 x 10(7)) were mixed with the spleen cells (1 x 10(7)), which were camouflaged or not camouflaged with mPEG, were transplanted into irradiated leukemia mice in C and D groups. GVL effects were assessed by L615 cells proportion in peripheral blood, histopathological changes and survival time.

RESULTSSevere GVHD was observed in group C (without mPEG modification), and the mice rapidly died, the mean survival time was 6.9 days. The mice in irradiated group (group B) with leukemia cell died of leukemia. The average survival time of group D (with mPEG modification) was 24.2 days, which was longer than that of the other groups (P < 0.05), and the survival rate of group D (27%) was significantly higher than that of the others (P < 0.05), 11 mice (11/15) died of leukemia and the others were still alive.

CONCLUSIONThe camouflage with mPEG modification is capable of preserving GVL effect and preventing GVHD in mice BMT.