Ontogeny of Xenopus NK cells in the absence of MHC class I antigens
Ontogeny of Xenopus NK cells in the absence of MHC class I antigens
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DOI：
10.1016/s0145-305x(03)00040-5
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发表时间：
2003-09-01
影响因子：
2.9
通讯作者：
Horton, JD
中科院分区：
文献类型：
--
作者：
Horton, TL;Stewart, R;Horton, JD
本文通过对表达NK细胞抗原1F8的细胞进行表型分析和体外细胞毒性试验，探讨了对照和早期胸腺去化（Tx）非洲爪蟾（Xenopus laevis） NK细胞的个体发生。双色流式细胞术显示，少量1f8阳性脾细胞最早出现在幼虫生命晚期，大约在受精后7周。这是在第一次检测到表面MHC la类表达后约2周。在3-4个月大的小青蛙中，表达1F8的脾细胞比例仍然很低，但到1岁时，有相当大的1F8阳性群体，在Tx青蛙中比例升高。NK细胞功能的发生是通过5 It DNA片段（JAM）测定来监测的。对照和Tx幼虫脾细胞（来自5周或7周大的蝌蚪）不能杀死mhc缺陷胸腺源性肿瘤细胞靶标。与年老青蛙脾细胞介导的高水平肿瘤细胞毒性相比，这种体外杀伤在3-4个月的小青蛙中仍然相对较差。免疫沉淀研究发现，1F8单抗的主要配体是一个55 kDa的多肽。最后，进一步的证据表明，1f8阳性淋巴细胞确实是真正的NK细胞，不同于T细胞，因为从爪蟾中纯化的1f8阳性脾细胞不能表达完全重排的TCRP V区转录物。我们得出的结论是，NK细胞在MHC I类蛋白表达之前不能发育，因此对幼虫的免疫系统没有贡献，而它们确实通过促进抗肿瘤免疫为成年青蛙的T细胞提供了重要的支持。2003爱思唯尔科学有限公司版权所有。
This paper explores the ontogeny of NK cells in control and early-thymectomized (Tx) Xenopus laevis through phenotypic analysis of cells expressing the NK cell antigen 1F8 and by performing in vitro cytotoxic assays. Dual color flow cytometry reveals that a few 1F8positive splenocytes first emerge in late larval life, at similar to 7-weeks post-fertilization. This is about 2-weeks after the time when surface MHC class la expression can first be detected. The proportion of splenocytes expressing 1F8 remains very low in 3-4 month-old froglets, but by 1 year there is a sizeable 1F8positive population, which is proportionally elevated in Tx frogs. The ontogeny of NK cell function is monitored by a 5 It DNA fragmentation (JAM) assay. Control and Tx larval splenocytes (from either 5- or 7-week-old tadpoles) fail to kill MHC-deficient thymus-derived tumor cell targets. Such in vitro killing is still relatively poor in 3-4 month froglets, compared with high levels of tumor cell cytotoxicity mediated by splenocytes from older frogs. Immunoprecipitation studies identify that the major ligand for the 1F8 mAb is a 55 kDa polypeptide. Finally, further evidence is provided that 1F8positive lymphocytes are indeed bona fide NK cells, distinct from T cells, since purified 1F8positive splenocytes from Tx Xenopus fail to express fully rearranged TCRP V region transcripts. We conclude that NK cells fail to develop prior to MHC class I protein expression and, therefore, do not contribute to the larval immune system, whereas they do provide an important backup for T cells in the adult frog by contributing to anti-tumor immunity. (C) 2003 Elsevier Science Ltd. All rights reserved.