Previous studies of NK cell inhibitory Ly49 receptors suggested their expression is stochastic. However, relatively few studies have examined this stochasticity in conjunction with activating Ly49 receptors. We hypothesized that the expression of activating Ly49 receptors is not stochastic and is influenced by inhibitory Ly49 receptors. We analyzed NK cell clusters defined by combinatorial expression of activating (Ly49H, Ly49D) and inhibitory (Ly49I, Ly49G2) receptors in C57BL/6 mice. Using the product rule to evaluate the interdependencies of the Ly49 receptors, we found evidence for a tightly regulated expression at the immature NK cell stage, with the highest interdependencies between clusters that express at least one activating receptor. Further analysis demonstrated that certain NK clusters predominated at the immature (CD27+CD11b-), transitional (CD27+CD11b+) and mature (CD27-CD11b-) NK cell stages. Using parallel in vitro culture and in vivo transplantation of sorted NK clusters, we discovered non-random upregulation of Ly49 receptors, suggesting that prescribed pathways of NK cluster differentiation exist. Our data infer that upregulation of Ly49I is an important step in NK cell maturation. Ki-67 expression and cell counts confirmed that immature NK cells proliferate more than mature NK cells. We found that MHC-I is particularly important for regulation of Ly49D and Ly49G2, even though no known MHC-I ligand for these receptors is present in B6 mice. Our data indicate that the regulatory systems controlling the expression of both activating and inhibitory Ly49 receptors are non-stochastic and support the idea that NK cell clusters develop in a non-random process correlated to their maturation stage.

中文翻译：

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小鼠中规定的NK细胞Ly49发育途径的证据

先前对NK细胞抑制Ly49受体的研究表明它们的表达是随机的。然而，很少有研究结合激活Ly49受体来检验这种随机性。我们假设激活的Ly49受体的表达不是随机的，并且受抑制性Ly49受体的影响。我们分析了在C57BL / 6小鼠中激活（Ly49H，Ly49D）和抑制性（Ly49I，Ly49G2）受体的组合表达所定义的NK细胞簇。使用乘积法则评估Ly49受体的相互依赖性，我们发现在未成熟NK细胞阶段表达受到严格调节的证据，在表达至少一种激活受体的簇之间具有最高的相互依赖性。进一步的分析表明，某些NK簇在未成熟（CD27 + CD11b-）处居主导地位，过渡（CD27 + CD11b +）和成熟（CD27-CD11b-）NK细胞阶段。使用平行的体外培养和分类的NK簇的体内移植，我们发现Ly49受体的非随机上调，表明存在NK簇分化的规定途径。我们的数据表明，Ly49I的上调是NK细胞成熟的重要步骤。Ki-67表达和细胞计数证实，未成熟的NK细胞比成熟的NK细胞增殖更多。我们发现，即使在B6小鼠中不存在针对这些受体的已知MHC-1配体，MHC-1对于调节Ly49D和Ly49G2也特别重要。