STEM CELL AGE AND X-RAY CHEMOTHERAPY LEUKEMOGENESIS

X射线/烷化剂诱导白血病的机制尚不清楚。 小鼠长期骨髓培养或克隆性慢性暴露 白介素3依赖的多潜能造血祖细胞 线到十万分之一到十万分之一摩尔 L-苯丙氨酸芥末(L-PAM)体外24个月的诱变 具有包括稳定标记染色体在内的异常的细胞系， 一万倍的IL-3生长需求减少，并改变了 对红系/嗜碱性粒细胞/中性粒细胞系的分化能力，但 在体内没有检测到的致白血病作用。相比之下，十万分之一的人 至十万分之一的L-PAM照射或50-500Gyx射线照射 纯化的骨髓基质细胞培养或克隆基质细胞系诱导 相同IL-3依赖系在琼脂上的集落形成 -10万，在系统中没有检测到IL-3的情况下。的 300个分离和传代的菌落，其中25个是IL-3 独立的25例中有3例在体外产生了白血病。连续式 覆盖的造血靶细胞需要暴露14-21天 用这种致白血病基质因子诱导可检测到的转化 (LSF)。我们现在建议阐明所涉及的基质细胞表型(S) 以及造血干细胞体液间接转化的机制 细胞经L-PAM处理或X射线照射后的骨髓基质细胞。方法将 包括蛋白质生物化学；长期骨髓培养；纯化 基质和造血干细胞培养自；对照，以前 辐照或烷化剂处理的小鼠.检验 粒细胞-巨噬细胞前体细胞(GM-CFUc)，多潜能 造血干细胞重建试验、脾细胞集落形成试验 (CFU)，以及体内克隆性细胞系的白血病产生能力的测定。这些 研究应该有助于阐明辐射和烷基化的机制 联合化疗和联合化疗后存活患者的诱导白血病 恶性肿瘤的放射治疗。

The mechanism of x-ray/alkylating agent induced leukemia is unknown. Chronic exposure of murine long-term bone marrow cultures or clonal Interleukin-3 (IL-3) dependent multipotential hematopoietic progenitor cell lines to one-ten-millionth to one one-hundred thousandth molar L-Phenylalanine Mustard (L-PAM) over 24 months in vitro induces variant cell lines with abnormalities including stable marker chromosomes, ten-thousandfold decreased IL-3 growth requirement, and altered differentiation capacity to erythroid/basophil/neutrophil lineages, but with no detectable in vivo leukemogenicity. In contrast, one-ten-millionth to one one-hundred thousandth L-PAM exposure or 50-500 Gy x-irradiation of purified marrow stromal cultures or a clonal stromal cell line induces colony formation by the same IL-3 dependent lines in agar overlay at -one-hundred thousand in the absence of detectable IL-3 in the system. Of 300 such individually removed and subcultured colonies, 25 were IL-3 independent and 3 of the 25 produced leukemia in vitro. Continuous exposure of overlaid hematopoietic target cells for 14-21 days was required to induce detectable transformation by this leukemogenic stromal factor (LSF). We now propose to elucidate the stromal cell phenotype(s) involved and the mechanism of humoral indirect transformation of hematopoietic stem cells by L-PAM treated or x-irradiated marrow stromal cells. Methods will include protein biochemistry; long-term bone marrow cultures; purified stromal and hematopoietic stem cell cultures from; control, previously irradiated or alkylating agent treated mice; assays for granulocyte-macrophage progenitor cells (GM-CFUc), pluripotential hematopoietic stem cells by reconstitution assay, spleen colony assay (CFUs), and assays for leukemogenecity of clonal cell lines in vivo. These studies should help elucidate the mechanism of irradiation and alkylating induced leukemia in patients surviving combination chemotherapy and irradiation therapy for malignancy.