Major histocompatibility complex (MHC) class II-associated invariant chain is a chaperone responsible for targeting the MHC class II dimer to the endocytic pathway, thus enabling the loading of exogenous antigens onto the MHC class II receptor. In the current study, in vivo and in vitro methods were used to investigate the regulation of the rainbow trout invariant chain proteins S25-7 and INVX, upon immune system activation. Whole rainbow trout and the macrophage/monocyte-like cell line RTS11 were treated with PMA at concentrations shown to induce IL-1β transcripts and homotypic aggregation of RTS11. S25-7 transcript levels remained unchanged in the gill, spleen, and liver and were found to be significantly decreased in head kidney beginning 24 h post-stimulation. Meanwhile, INVX transcript levels remained unchanged in all tissues studied. Both S25-7 and INVX proteins were produced in gill and spleen tissues but their expression was unaffected by immune system stimulation. Surprisingly, neither INVX nor S25-7 protein was detected in the secondary immune organ, the head kidney. Analysis of RTS11 cultures demonstrated that both INVX and S25-7 transcript levels significantly increased at 96 h and 120 h following PMA stimulation before returning to control levels at 168 h. Meanwhile, at the protein level in RTS11, S25-7 remained unchanged while INVX had a significant decrease at 168 h post-stimulation. These results indicate that neither INVX nor S25-7 is upregulated upon immune system activation; thus, teleosts have evolved a system of immune regulation that is different than that found in mammals.

中文翻译：

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虹鳟鱼的免疫刺激揭示了与MH II类相关的恒定链同工型的不同调节。

主要的组织相容性复合体（MHC）II类相关的恒定链是负责将MHC II类二聚体靶向内吞途径的分子伴侣，从而能够将外源抗原加载到MHC II类受体上。在当前的研究中，体内和体外方法被用于研究免疫系统激活后虹鳟不变链蛋白S25-7和INVX的调控。用PMA处理整个虹鳟鱼和巨噬细胞/单核细胞样细胞系RTS11，其浓度可诱导IL-1β转录本和RTS11的同型聚集。S25-7转录物水平在the，脾脏和肝脏中保持不变，并且在刺激后24小时开始在头肾中显着降低。同时，在所有研究的组织中INVX转录物水平保持不变。S25-7和INVX蛋白均在g和脾组织中产生，但它们的表达不受免疫系统刺激的影响。出人意料的是，在次要免疫器官，即头部肾脏中，未检测到INVX和S25-7蛋白。对RTS11培养物的分析表明，PMA刺激后96h和120h，INVX和S25-7转录物水平均显着增加，然后在168h恢复至对照水平。同时，在RTS11的蛋白质水平上，S25-7保持不变，而INVX在刺激后168 h显着下降。这些结果表明，免疫系统激活后，INVX和S25-7均未上调。因此，硬骨鱼类已发展出一种与哺乳动物不同的免疫调节系统。