Spangrude G J, Brooks D M
Laboratory of Persistent Viral Diseases, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, MT 59840.
Blood. 1993 Dec 1;82(11):3327-32.
The cell surface molecule Ly-6A/E provides a convenient marker for primitive stem cells in the hematopoietic tissues of both fetal and adult mice. However, previous studies have shown that Ly-6A/E expression by lymphocytes is variable depending on the haplotype of the Ly-6 locus. Therefore, strain-specific variation in Ly-6A/E expression by bone marrow (BM) cells was investigated. The results show that Ly-6a mice have, on average, 50% of the number of BM cells expressing Ly-6A/E relative to that for Ly-6b mice. Furthermore, among the 5% of BM cells that do not express antigens characteristic of mature T, B, myeloid, or erythroid lineages, which include the primitive hematopoietic stem cell compartment, Ly-6a mice have, on average, more than fivefold fewer Ly-6A/E+ cells relative to that for Ly-6b mice. Isolation of Ly-6A/E- and Ly-6A/E+ cells from mice of both haplotypes showed that, whereas 99% of the marrow repopulating activity (MRA) of C57BL/Ka (Ly-6b) mice could be recovered in the Ly-6A/E+ fraction, only about 25% of the MRA of BALB/c (Ly-6a) was recoverable in the same population. On a per-cell basis, the Ly-6A/E+ cells that were isolated from BALB/c mice were essentially equivalent in MRA to those isolated from C57BL/Ka mice. Thus, whereas a large percentage of the hematopoietic stem cells of Ly-6a mice do not express the Ly-6A/E molecule, the antigen may be used to isolate a subset of stem cells from these mice. These results show that hematopoietic stem cell phenotype can vary between mouse strains and imply that caution should be exercised in the identification of human stem cell antigens such as CD34, because a similar variability may occur between individual humans. To further explore the influence of Ly-6 haplotype on Ly-6A/E expression by specific cell subsets, lymph-node lymphocytes from a panel of mouse strains were analyzed by multiparameter flow cytometry for correlated expression of Ly-6A/E, CD4, and CD8. All Ly-6a strains examined had less than 20% Ly-6A/E+ cells, and those cells were predominantly CD8+ T lymphocytes. In contrast, the Ly-6b strains had greater than 30% Ly-6A/E+ cells, and those cells included CD4+, CD8+, and B lymphocytes.
细胞表面分子Ly-6A/E为胎儿和成年小鼠造血组织中的原始干细胞提供了一种便捷的标志物。然而，先前的研究表明，淋巴细胞中Ly-6A/E的表达因Ly-6基因座的单倍型而异。因此，研究了骨髓（BM）细胞中Ly-6A/E表达的品系特异性差异。结果显示，相对于Ly-6b小鼠，Ly-6a小鼠中表达Ly-6A/E的BM细胞数量平均只有其50%。此外，在5%不表达成熟T、B、髓系或红系谱系特征性抗原的BM细胞中，其中包括原始造血干细胞区室，相对于Ly-6b小鼠，Ly-6a小鼠中Ly-6A/E+细胞的数量平均减少了五倍多。从两种单倍型小鼠中分离Ly-6A/E-和Ly-6A/E+细胞显示，虽然C57BL/Ka（Ly-6b）小鼠99%的骨髓再填充活性（MRA）可在Ly-6A/E+组分中恢复，但BALB/c（Ly-6a）小鼠的MRA在同一群体中只有约25%可恢复。以每个细胞为基础，从BALB/c小鼠中分离的Ly-6A/E+细胞在MRA方面与从C57BL/Ka小鼠中分离的细胞基本相当。因此，虽然Ly-6a小鼠中很大比例的造血干细胞不表达Ly-6A/E分子，但该抗原可用于从这些小鼠中分离出一部分干细胞。这些结果表明，造血干细胞表型在小鼠品系之间可能存在差异，这意味着在鉴定人类干细胞抗原如CD34时应谨慎，因为个体之间可能会出现类似的变异性。为了进一步探究Ly-6单倍型对特定细胞亚群Ly-6A/E表达的影响，通过多参数流式细胞术分析了一组小鼠品系的淋巴结淋巴细胞中Ly-6A/E、CD4和CD8的相关表达。所有检测的Ly-6a品系中Ly-6A/E+细胞均少于20%，且这些细胞主要是CD8+T淋巴细胞。相比之下，Ly-6b品系中Ly-6A/E+细胞大于30%，且这些细胞包括CD4+、CD8+和B淋巴细胞。
