Makrigiannis A P, Pau A T, Saleh A, Winkler-Pickett R, Ortaldo J R, Anderson S K
Laboratory of Experimental Immunology, Division of Basic Sciences, and Intramural Research Support Program, Science Applications International Corp. Frederick, National Cancer Institute, Frederick, MD 21702, USA.
J Immunol. 2001 Apr 15;166(8):5034-43. doi: 10.4049/jimmunol.166.8.5034.
The Ly49 family of NK cell receptors and its MHC-binding characteristics have only been well characterized in C57BL/6 (B6) mice. Previous studies have shown that 129/J mice express unique Ly49 genes that are not found in the B6 strain. Screening of a 129/J cDNA library led to the discovery of 10 distinct full-length Ly49-related coding sequences (Ly49e, g, i, o, p, r, s, t, u, and v). Although 129/J mice share identical class I MHC (K(b) and D(b)) transcripts with B6 mice, only one Ly49 is identical in the two strains (Ly49E). In addition to the previously characterized Ly49P, two new activating Ly49 proteins were discovered, Ly49R and U. The MHC specificity of the total 129/J Ly49 repertoire was evaluated with soluble class I MHC tetramers and found to be distinct compared with the B6 Ly49 repertoire. Ly49V bound to many types of class I MHC, suggesting that Ly49V(+) NK cells may monitor host cells for a global down-regulation in MHC levels. An activating receptor, Ly49R, was shown to bind soluble class I molecules to a moderate degree, a result not previously observed for other activating Ly49 proteins. Furthermore, tetramer-binding results were confirmed functionally with cytotoxicity assays using sorted 129/J NK cells. This study shows that the Ly49 repertoire and its MHC-binding characteristics can be very different among inbred mouse strains. Ly49 divergence should be considered when using 129-derived embryonic stem cells for the production of gene-targeted mice, especially when an immune or NK-derived phenotype is under scrutiny.
NK细胞受体的Ly49家族及其与MHC结合的特性仅在C57BL/6（B6）小鼠中得到充分表征。先前的研究表明，129/J小鼠表达B6品系中未发现的独特Ly49基因。对129/J cDNA文库的筛选导致发现了10个不同的全长Ly49相关编码序列（Ly49e、g、i、o、p、r、s、t、u和v）。尽管129/J小鼠与B6小鼠共享相同的I类MHC（K(b)和D(b)）转录本，但两个品系中只有一种Ly49是相同的（Ly49E）。除了先前表征的Ly49P外，还发现了两种新的激活型Ly49蛋白，即Ly49R和U。用可溶性I类MHC四聚体评估了129/J小鼠Ly49全部组成的MHC特异性，发现与B6小鼠的Ly49全部组成不同。Ly49V与多种类型的I类MHC结合，这表明Ly49V(+) NK细胞可能监测宿主细胞MHC水平的整体下调情况。一种激活受体Ly49R被证明能与可溶性I类分子中度结合，这一结果在其他激活型Ly49蛋白中未曾观察到。此外，使用分选的129/J NK细胞进行细胞毒性试验在功能上证实了四聚体结合结果。这项研究表明，近交小鼠品系间Ly49全部组成及其与MHC结合的特性可能有很大差异。当使用源自129的胚胎干细胞生产基因靶向小鼠时，尤其是在研究免疫或NK细胞衍生的表型时，应考虑Ly49的差异。
