[Treatment of leukemia with immunized donor cell infusion after nonmyeloablative haploidentical bone marrow transplantation].

This study was purposed to investigate the therapeutic effects of early transfusion of immunized donor lymphocytes after haploidentical transplantation by means of mouse model of nonmyeloablative haploidentical bone marrow transplantation. CB6F1 female mouse was served as recipient and C57BL/6 male mouse was served as donor. Each CB6F1 female mouse was subjected to intravenous transfusion with 1×10(6) erythroleukemia (EL9611) cells at day 4 before transplantation, followed with intraperitoneal injection of Ara-C (0.015 g) respectively at day 2 and day 1, then conditioned for BMT with TBI (450 cGy) at day 1 before transplantation. After conditioning (day 0), each of recipients was transplanted with 6×10(7) mixture of bone marrow and spleen cells from the C57BL/6 mice, and was infused with 6 × 10(7) immunized donor lymphocytes at day 15 after transplantation. All treated animals were evaluated for survival, development of leukemia and aGVHD. The donor CD3(+) cell chimerism and sex determining region Y gene (SRY)in recipients were monitored periodically after transplantation. The results showed tht all mice with only inoculation of 10(6) EL9611 cells survived for 15 ± 1 days (n = 4); all mice of other groups obtained the varying degrees of implantation. SRY could be detected at day 30 and 60 after transplantation. The chimerism of donor CD3(+) cells in mixed bone marrow transplantation (MT) group at day 14, 30 and 60 respectively reached 17.95% ± 12.03%, 37.34% ± 2.78% and 47.06% ± 6.1%. In donor lymphocyte infusion (DLI) group it reached 69.78% ± 12.62%, 75% ± 15.97%, 83.41% ± 16.07% at day 30, 45 and 60 after transplantation. The mice of MT and DLI group survived for 66.66 ± 1.47 days and 78.2 ± 7.82 days. It is concluded that the high tumor burden before transplantation can affect donor cell engraftment and prognosis.Early post-transplanted infusion of immunized lymphocytes from donor can help to improve the therapeutic efficacy and survival.