Effects of natural killer cells on engraftment and reconstitution of hematopoiesis and immunity in mice undergoing allogeneic bone marrow transplantation / 中国实验血液学杂志

ABSTRACT

The aim of this study was explore the effect of natural killer (NK) cells on engraftment and reconstitution of hematopoiesis and immunity in mice undergoing allogeneic bone marrow transplantation (allo-BMT). Lethally and nonlethally irradiated BALB/c (H-2(d)) mice were transplanted with C57BL/6 (H-2(b)) bone marrow plus donor peripheral T cells and/or NK cells. Recipient CD34(+), H-2K(b+), CD3(+) and CD19(+) cells were detected by flow cytometry; peripheral blood leukocytes were counted by auto-cytometry; survival rates, engraftment, hematopoietic and immune recovery of recipients in different transplant groups were then observed. The results indicated that as compared with lethally irradiated and allo-BMT group without infusion of NK cells, the survival rate in lethally irradiated and allo-BMT group with infusion of NK cells significantly enhanced (survival rates at 60 days were 70% and 0.0% respectively); leukocyte count, expression level of CD19(+) cell and CD34(+) cell count recovered rapidly; expression level of H-2K(b+) cells obviously increased [(86.68 +/- 4.45)% vs (4.68 +/- 0.32)%]; expression level of CD3(+) cell at day 28 after transplantation obviously decreased [(33.69 +/- 3.36)% vs (50.40 +/- 5.06)%, p < 0.01], at day 60 there was not significant difference between the 2 groups (p > 0.05). In nonlethally irradiated and allo-BMT group without NK cell infusion, the expression level of H-2K(b+) at day 30 after transplantation significantly decreased, and reduced to level before transplantation at day 60; while expression of H-2K(b+) yet could be detected with > 80% at day 60 after transplantation in group infused with high and low concentration of NK cells. It is concluded that in allo-BMT mice, alloreactive NK cell inhibits graft rejection, enhances engraftment, promotes the reconstitution of hematopoiesis and immunity, and increases survival rates.