Van Voorhis W C, Schlekewy L, Trong H L
Department of Medicine, University of Washington, Seattle 98195.
Proc Natl Acad Sci U S A. 1991 Jul 15;88(14):5993-7. doi: 10.1073/pnas.88.14.5993.
Antigenic mimicry by Trypanosoma cruzi antigens that share epitopes with mammalian tissues may drive autoreactive B- or T-cell clones to expand and cause autoimmune pathogenesis. We have been studying one of these antigens, F1-160, a 160-kDa protein on the surface of T. cruzi that antigenically mimics a 48-kDa protein found in mammalian axonal and myenteric plexus cells. The F1-160 antigen has been characterized by cloning and expression of T. cruzi DNA encoding F1-160 in Escherichia coli. Recombinant peptides from various regions of the F1-160 gene were expressed and used to compete with affinity-purified polyclonal anti-F1-160 antibodies binding to nerve. Recombinant 48-amino acid peptide (48X) derived from expression of base pairs 611-761 of the DNA sequence completely inhibited anti-F1-160 binding to nerve. Recombinant peptides expressed from DNA lacking this region did not inhibit anti-F1-160 binding to nerve. Three peptides were synthesized to encompass the 48X peptide, a 12-amino acid peptide and two 18-amino acid peptides. The 12-amino acid peptide TPQRKTTEDRPQ (12X), corresponding to bases 615-651, completely inhibited the binding of anti-F1-160 antibodies to nerve at a concentration of 80 ng/ml (30 microM). The two 18-residue peptides did not inhibit, even at 10 micrograms/ml. Thus, the epitope of F1-160 crossreactive with nervous tissue can be mapped to a 12-amino acid peptide. Some humans with T. cruzi infection make antibodies to F1-160 and to the 48X and 12X peptides. Control sera from uninfected persons did not react with these antigens. Anti-48X antibodies, immunoselected from human serum with 48X peptide, bind to human nerve axons. This demonstrates that some individuals infected with T. cruzi make antibodies to the F1-160 epitope crossreactive with nervous tissues.
克氏锥虫的抗原与哺乳动物组织共享表位，这种抗原模拟可能会促使自身反应性B细胞或T细胞克隆扩增，从而引发自身免疫性发病机制。我们一直在研究其中一种抗原F1 - 160，它是克氏锥虫表面的一种160 kDa蛋白，在抗原性上模拟了在哺乳动物轴突和肌间神经丛细胞中发现的一种48 kDa蛋白。F1 - 160抗原已通过在大肠杆菌中克隆和表达编码F1 - 160的克氏锥虫DNA进行了表征。从F1 - 160基因的各个区域表达的重组肽被用于与亲和纯化的多克隆抗F1 - 160抗体结合神经的反应进行竞争。从DNA序列的611 - 761碱基对表达产生的重组48氨基酸肽（48X）完全抑制了抗F1 - 160与神经的结合。从缺乏该区域的DNA表达的重组肽没有抑制抗F1 - 160与神经的结合。合成了三种肽以包含48X肽、一个12氨基酸肽和两个18氨基酸肽。对应于碱基615 - 651的12氨基酸肽TPQRKTTEDRPQ（12X）在浓度为80 ng/ml（30 microM）时完全抑制了抗F1 - 160抗体与神经的结合。即使在10微克/毫升的浓度下，这两个18个残基的肽也没有抑制作用。因此，与神经组织交叉反应的F1 - 160的表位可以定位到一个12氨基酸肽。一些感染克氏锥虫的人会产生针对F1 - 160以及48X和12X肽的抗体。未感染个体的对照血清与这些抗原不发生反应。用48X肽从人血清中免疫选择的抗48X抗体与人类神经轴突结合。这表明一些感染克氏锥虫的个体产生了针对与神经组织交叉反应的F1 - 160表位的抗体。
