PHENOTYPIC CHARACTERIZATION OF EARLY EVENTS OF THYMUS REPOPULATION IN RADIATION BONE MARROW CHIMERAS
PHENOTYPIC CHARACTERIZATION OF EARLY EVENTS OF THYMUS REPOPULATION IN RADIATION BONE MARROW CHIMERAS
复制标题
辐射骨髓嵌合体中胸腺再生早期事件的表型特征
作者：
S. Sharrow;A. Singer;U. Hammerling;B. Mathieson
用免疫荧光和流式显微荧光法分析了辐射骨髓嵌合体照射后即刻胸腺重新填充的海洋胸腺细胞表型。这些嵌合体中的胸腺，虽然在第7天基本上没有淋巴样细胞，但在照射后第10到12天又被重新填充。研究发现，这种最初的重新繁殖起源于胸腺内的一种抗辐射前体，该前体扩展到几乎完全的宿主类型胸腺细胞。然而，这些宿主来源的胸腺细胞是不寻常的，因为与正常胸腺细胞相比，它们在Lyt1+2-和花生凝集素“迟钝”细胞中相对缺乏。供体骨髓来源的细胞在照射和骨髓移植后12-15天首次出现在照射后的嵌合胸腺中。到第19天，嵌合胸腺含有98%以上的供体细胞。这一过程对于三种嵌合组合来说是相同的，每种嵌合组合都跨越了不同的基因障碍。与正常个体发育期间胎儿胸腺中的细胞不同，在照射后的嵌合胸腺中可以检测到的第一批供者骨髓来源的细胞已经表达了表型正常的成人T细胞亚群，因为它们包含大量的Lyt1+2-和Lyt1+2+胸腺细胞。因此，照射后最初填充成人胸腺的供体细胞的Lyt表型与最初填充胎儿胸腺的细胞的Lyt表型明显不同。在辐射骨髓嵌合体中观察到的成人和胎儿胸腺发育的差异可能对我们理解这些动物的T细胞分化很重要。
The phenotype of marine thymocytes repopulating the thymus of radiation bone marrow chimeras shortly after irradiation and bone marrow reconstitution was analyzed by immunofluorescence and flow microfluorometry. Thymuses in these chimeras, while essentially devoid of lymphoid cells at day 7, were repopulated by days 10 to 12 after irradiation. It was found that this initial repopulation arose from a radioresistant intrathymic precursor that expanded to an almost complete complement of host-type thymocytes. However, these host-derived thymocytes were unusual in that they were relatively deficient in Lyt 1+2- and peanut agglutinin “dull” cells as compared with normal thymocytes. Donor bone-marrow-derived cells first appeared in the irradiated chimeric thymuses between days 12 and 15 after irradiation and bone marrow transfer. By day 19, chimeric thymuses contained more than 98% donor cells. This course was identical for three chimeric combinations, each made across different genetic barriers. In contrast to the cells that populate the fetal thymus during normal ontogeny, the first donor bone-marrow-derived cells that can be detected within the irradiated chimeric thymuses already expressed phenotypically normal adult T cell subpopulations in that they contained significant numbers both of Lyt 1+2- and of Lyt 1+2+ thymocytes. Thus, the Lyt phenotype of donor cells that initially repopulate an adult thymus after irradiation is markedly different from the Lyt phenotype of cells that initially populate the fetal thymus. The differences between adult and fetal thymic development that are observed in radiation bone marrow chimeras may be important in our understanding of T cell differentiation in these animals.