Lapidot T, Terenzi A, Singer T S, Salomon O, Reisner Y
Départment of Biophysics, Weizmann Institute of Science, Rehovot, Israel.
Blood. 1989 May 15;73(7):2025-32.
A major problem in using murine models for studies of bone marrow allograft rejection in leukemia patients is the narrow margin in which graft rejection can be analyzed. In mice irradiated with greater than 9 Gy total body irradiation (TBI) rejection is minimal, whereas after administration of 8 Gy TBI, which spares a significant number of clonable T cells, a substantial frequency of host stem cells can also be detected. In current murine models, unlike in humans, bone marrow allograft rejection is generally associated with full autologous hematopoietic reconstitution. In the present study, we investigated the effect of the myeloablative drug dimethyl myleran (DMM) on chimerism status following transplantation of T cell-depleted allogenic bone marrow (using C57BL/6 donors and C3H/HeJ recipients, conditioned with 8 Gy TBI). Donor type chimerism 1 to 2 months post-transplant of 1 to 3 x 10(6) bone marrow cells was markedly enhanced by using DMM one day after TBI and prior to transplantation. Conditioning with cyclophosphamide instead of DMM, in combination with 8 Gy TBI, did not enhance engraftment of donor type cells. Artificial reconstitution of T cells, after conditioning with TBI plus DMM, by adding mature thymocytes, or presensitization with irradiated donor type spleen cells 1 week before TBI and DMM, led to strong graft rejection and consequently to severe anemia. The anti-donor responses in these models were proportional to the number of added T cells and to the number of cells used for presensitization, and they could be neutralized by increasing the bone marrow inoculum. These results demonstrate the potential of DMM to facilitate engraftment in unsensitized mice in which the host stem cells may compete with donor type cells; the use of DMM to create models in which mechanisms of immune rejection can be studied without interference due to stem cell competition; and that bone marrow allograft rejection may be overcome by increasing the bone marrow inoculum in these stringent models.
在使用小鼠模型研究白血病患者骨髓同种异体移植排斥反应时，一个主要问题是分析移植排斥反应的范围很窄。在用大于9 Gy全身照射（TBI）的小鼠中，排斥反应最小，而在给予8 Gy TBI后，由于保留了大量可克隆的T细胞，也能检测到相当比例的宿主干细胞。在当前的小鼠模型中，与人类不同，骨髓同种异体移植排斥反应通常与完全自体造血重建相关。在本研究中，我们研究了清髓药物二甲磺酸丁酯（DMM）对T细胞去除的同种异体骨髓移植（使用C57BL/6供体和C3H/HeJ受体，用8 Gy TBI预处理）后嵌合状态的影响。在TBI后一天和移植前使用DMM，可显著增强移植1至3×10(6)个骨髓细胞后1至2个月的供体类型嵌合。用环磷酰胺代替DMM并结合8 Gy TBI进行预处理，并没有增强供体类型细胞的植入。在用TBI加DMM预处理后，通过添加成熟胸腺细胞人工重建T细胞，或在TBI和DMM前1周用照射过的供体类型脾细胞进行预致敏，会导致强烈的移植排斥反应，进而导致严重贫血。这些模型中的抗供体反应与添加的T细胞数量和用于预致敏的细胞数量成正比，并且可以通过增加骨髓接种量来中和。这些结果表明，DMM有潜力促进未致敏小鼠的植入，在这些小鼠中宿主干细胞可能与供体类型细胞竞争；使用DMM创建模型，在该模型中可以研究免疫排斥机制而不受干细胞竞争的干扰；并且在这些严格的模型中，通过增加骨髓接种量可以克服骨髓同种异体移植排斥反应。
