Naujokas M F, Arneson L S, Fineschi B, Peterson M E, Sitterding S, Hammond A T, Reilly C, Lo D, Miller J
Department of Molecular Genetics and Cell Biology, University of Chicago, Illinois 60637, USA.
Immunity. 1995 Sep;3(3):359-72. doi: 10.1016/1074-7613(95)90120-5.
Invariant chain (Ii)-negative mice exhibit defects in MHC class II assembly and transport that results in reduced levels of surface class II, altered antigen presentation, and inefficient positive selection of CD4+ T cells. Many CD4+ T cells that do mature in Ii-negative mice express a cell surface phenotype consistent with aberrant positive selection or peripheral activation. Reconstitution of these mice with low levels of either the p31 or p41 form of Ii does not restore transport of the bulk of class II or class II surface expression, but surprisingly does restore positive selection as measured by numbers and surface phenotype of CD4+ T cells. Thus, an Ii-dependent process, independent of effects on class II surface density, appears to be required for normal positive selection of CD4+ T cells.
恒定链（Ii）缺陷小鼠在MHC II类分子组装和运输方面存在缺陷，导致表面II类分子水平降低、抗原呈递改变以及CD4+ T细胞阳性选择效率低下。许多在Ii缺陷小鼠中成熟的CD4+ T细胞表达的细胞表面表型与异常阳性选择或外周激活一致。用低水平的Ii的p31或p41形式重建这些小鼠，并不能恢复大部分II类分子的运输或II类分子的表面表达，但令人惊讶的是，通过CD4+ T细胞的数量和表面表型测量，确实恢复了阳性选择。因此，正常的CD4+ T细胞阳性选择似乎需要一个依赖于Ii的过程，该过程独立于对II类分子表面密度的影响。
