Wu M X, Tsomides T J, Eisen H N
Department of Biology, Massachusetts Institute of Technology, Cambridge 02139, USA.
J Immunol. 1995 May 1;154(9):4495-502.
The peptides recognized by CD8+ CTL normally arise by proteolysis of intracellular proteins. To learn whether these peptides are generated similarly in diverse cell types, we examined the variety and abundance of naturally processed peptides that derive from a ubiquitous enzyme, alpha-ketoglutarate dehydrogenase, and are recognized in association with the class I MHC protein, Ld, by a CTL clone (2C). A characteristic set of three peptides was found in diverse tissues, but their abundance varied greatly, apparently unrelated to differences in class I MHC expression, e.g., they were surprisingly abundant in liver. We also found in liver a fourth naturally processed peptide (p2Ca-Y4, LSPYPFDL) that differs by one oxygen atom from a previously characterized natural peptide (p2Ca, LSPFPFDL). CTL discrimination between these peptides in association with the same class I MHC protein, Kb, demonstrates the striking specificity that can be exhibited by low affinity T cell reactions.
CD8⁺细胞毒性T淋巴细胞（CTL）识别的肽通常由细胞内蛋白质的蛋白水解产生。为了了解这些肽在不同细胞类型中是否以类似方式产生，我们研究了源自一种普遍存在的酶——α-酮戊二酸脱氢酶的天然加工肽的种类和丰度，这些肽与I类主要组织相容性复合体（MHC）蛋白Ld结合时可被一个CTL克隆（2C）识别。在不同组织中发现了一组特征性的三种肽，但它们的丰度差异很大，这显然与I类MHC表达的差异无关，例如，它们在肝脏中出人意料地丰富。我们还在肝脏中发现了第四种天然加工肽（p2Ca-Y4，LSPYPFDL），它与先前鉴定的一种天然肽（p2Ca，LSPFPFDL）相差一个氧原子。与同一I类MHC蛋白Kb结合时，CTL对这些肽的区分表明低亲和力T细胞反应可表现出惊人的特异性。
