Serwe M, Reuter G, Sponaas A, Koch S, Koch N
Section of Immunobiology, Institute of Zoology, University of Bonn, Germany.
Int Immunol. 1997 Jul;9(7):983-91. doi: 10.1093/intimm/9.7.983.
The invariant chain (Ii) gene encodes two differentially spliced variants Ii31 and Ii41. The Ii31 isotype is the dominant form expressed in all antigen-presenting cells (APC). Ii41 is differentially expressed and can be found in large quantities in Langerhans and dendritic cells. While a functional role of Ii in class II antigen presentation is now well established, a distinct role of the Ii isotypes remains controversial. We tested Ii31 and Ii41 L cell transfectants for antigen presentation of hen egg lysozyme (HEL) to T cell hybridomas. The result indicates that both Ii chains promote antigen presentation equally well. To test other APC than transfected L cells, we introduced a recombinant Ii41 gene into anti-deficient mouse line. There the transgene induces about one-third of total li expression of wild-type mice. Surface expression of class II molecules and the CD4 compartment which are deficient in Ii knock-out mice are restored in Ii41 transgenic mice. B lymphocytes from Ii41 transgenic mice and Ii31-expressing B lymphocytes from wild-type mice were used as APC for presentation of keyhole limpet hemacyanin and ovalbumin to T cell hybridomas. The results show that both Ii chains facilitate antigen presentation equally well.
恒定链（Ii）基因编码两种差异剪接变体Ii31和Ii41。Ii31同种型是在所有抗原呈递细胞（APC）中表达的主要形式。Ii41差异表达，在朗格汉斯细胞和树突状细胞中大量存在。虽然Ii在II类抗原呈递中的功能作用现已得到充分证实，但Ii同种型的独特作用仍存在争议。我们测试了Ii31和Ii41 L细胞转染子将鸡卵溶菌酶（HEL）呈递给T细胞杂交瘤的抗原呈递能力。结果表明，两条Ii链促进抗原呈递的能力同样良好。为了测试除转染的L细胞之外的其他APC，我们将重组Ii41基因导入Ii缺陷小鼠品系。在那里，转基因诱导的总Ii表达量约为野生型小鼠的三分之一。Ii41转基因小鼠恢复了Ii基因敲除小鼠中缺乏的II类分子和CD4区室的表面表达。来自Ii41转基因小鼠的B淋巴细胞和来自野生型小鼠的表达Ii31的B淋巴细胞被用作APC，将钥孔戚血蓝蛋白和卵清蛋白呈递给T细胞杂交瘤。结果表明，两条Ii链促进抗原呈递的能力同样良好。
