Fulop G M, Phillips R A
Department of Immunology, University of Toronto, Ontario, Canada.
Blood. 1989 Oct;74(5):1537-44.
Mice homozygous for an autosomal recessive scid (severe combined immune deficiency) mutation on chromosome 16 exhibit a defect that specifically impairs lymphoid differentiation but not myelopoiesis. Consequently such mice are deficient in both humoral and cell-mediated immune functions. Despite their defect, scid mice survive under pathogen-free conditions and are fertile. The mutation does not impair the hematopoietic microenvironment necessary for lymphoid differentiation, since these mice can be cured with grafts of normal bone marrow (BM) or cells from long-term BM cultures (LTBMC); however, reconstitution requires sublethal (400 cGy) irradiation of recipients. Engraftment with cells from LTBMC gave near-normal levels of colony-forming B cells (CFU-B) in spleen and BM of the recipients by 6 weeks postgrafting. Since LTBMC are devoid of all mature B and pre-B cells but contain stem cells that restore lymphoid function in scid mice, we used a limiting-dilution assay to characterize and enumerate the number of stem cells in LTBMC capable of restoring lymphoid function. Curing was determined by the CFU-B-cell assay, since CFU-B are not detectable in normal scid mice. The results indicate that fewer cells from LTBMC than from fresh BM are required to obtain lymphoid reconstitution. As few as 10(3) LTBMC cells can repopulate significant B- and T-cell function in scid recipients. From these results we conclude that scid mice can be used as recipients to quantify lymphoid-restricted stem cells and that there is a functional separation of lymphoid- and myeloid-restricted stem cells in LTBMC with an enrichment for lymphoid-restricted stem cells in these cultures.
在16号染色体上携带常染色体隐性scid（严重联合免疫缺陷）突变的纯合子小鼠表现出一种缺陷，该缺陷特异性损害淋巴细胞分化但不影响髓细胞生成。因此，此类小鼠的体液免疫和细胞介导免疫功能均有缺陷。尽管存在缺陷，scid小鼠在无病原体条件下仍能存活且可育。该突变并不损害淋巴细胞分化所必需的造血微环境，因为这些小鼠可用正常骨髓（BM）或长期骨髓培养物（LTBMC）中的细胞进行治愈；然而，重建需要对受体进行亚致死剂量（400 cGy）的照射。移植LTBMC细胞后6周，受体脾脏和骨髓中集落形成B细胞（CFU - B）的水平接近正常。由于LTBMC不含所有成熟B细胞和前B细胞，但含有能恢复scid小鼠淋巴细胞功能的干细胞，我们使用有限稀释分析法来表征和计数LTBMC中能够恢复淋巴细胞功能的干细胞数量。通过CFU - B细胞测定来确定治愈情况，因为在正常scid小鼠中检测不到CFU - B。结果表明，与新鲜BM相比，获得淋巴细胞重建所需的LTBMC细胞更少。低至10³个LTBMC细胞就能在scid受体中重建显著的B细胞和T细胞功能。从这些结果我们得出结论，scid小鼠可作为受体来定量淋巴细胞限制性干细胞，并且在LTBMC中存在淋巴细胞限制性和髓细胞限制性干细胞的功能分离，这些培养物中富含淋巴细胞限制性干细胞。
