[The action of donor-derived NK cell in leukemic mice MHC haplotype-mismatched bone marrow transplantation].

Objective: To study the role of donor-derived NK cells in haploidentical bone marrow transplantation (BMT) in leukemic mice.

Methods: CB6F1(H-2b/d) mice model of EL9611 (H-2d) erythroleukemia was established by injection of EL9611 (H-2d) cells via tail vein. CB6F1(H-2b/d) mice were used as recipient, and C57BL/6(H-2b) mice as donor. Five days later, 70 CB6F1(H-2b/d) mice were randomly divided into 7 groups (10 mice per group) as follows: group 1: without treatment; group 2: simple-irradiated group; group 3: treated with cytarabine (Ara-C) at 50 mg/kg x6 d; group 4: simple BMT; group 5: haploidentical BMT with graft-versus-host disease (GVHD) that injected with bone marrow cells and spleen cells of C57BL/6(H-2b) mice 4 hours after irradiation; group 6: after irradiated with 9 Gy, mice were injected with C57BL/6(H-2b) NK cells (1 x 10(6)) and 4 hours later with BM cells, group 7: after irradiation of 9 Gy, mice were injected with C57BL/6(H-2b) NK cells (1 x 10(6)) and 4 hours later with BM cells and spleen cells. The blood routine test, survival time, body weight, and histopathology in the recipients were observed and compared among these group.

Results: The survival time was (10.1 +/- 0.9), (9.8 +/- 0.9), (22.7 +/- 3.2) and (20.1 +/- 1.7) days in groups 1, 2, 3, and 5 respectively; was (30.1 +/- 16.0) days in group 4, out of which 2 mice survived for more than 30 days. The survival time was (39.1 +/- 18.1) and (49.3 +/- 17.2) days in groups 6 and 7 respectively, out of which 4 mice in group 6 and 7 mice in group 7 survived for more than 30 days. The survival time in group 6 was much longer than that in group 1, 2, 3 and 5 (P < 0.01). The survival time in group 7 was much longer than that in other groups (P < 0.05). The liver and spleen enlargement, organ destruction and infiltration with leukemic cells were observed in mice died from leukemia. The chimerism of Y chromosome appeared (80%-90%) in long-term survival mice in groups 6 and 7.

Conclusion: Donor-derived NK cells have the antileukemia ability and reduce GVHD in haploidentical BMT in erythroleukemia mice (EL9611, H-2d).