Agris P F, KiKuchi Y, Gross H J, Takano M, Sharp G C
Immunol Commun. 1984;13(2):137-49. doi: 10.3109/08820138409025457.
Small nuclear ribonucleoprotein complexes are antigens in various autoimmune diseases. The serological pattern of high titers of circulating antibody to nuclear ribonucleoprotein (RNP) antigen is a diagnostic marker for mixed connective tissue disease (MCTD); whereas antibody to Sm is prevalent in systemic lupus erythematosus (SLE). Both calf thymus and rabbit thymus are commonly used, excellent sources for preparation of the corresponding antigens RNP and Sm in clinical and research laboratories (A. M. Boak et al., accompanying paper). Thus, biochemical and structural characterization of the minimal antigenic determinant in these preparations is important for its use in the laboratory, as well as significant for understanding MCTD, SLE, and other examples of autoimmunity. Purification and biochemical analyses of immunologically active RNP from many different preparations of calf thymus extract has revealed that the majority of antibody in monospecific MCTD patient sera recognizes an antigen composed of the 165 nucleotide RNA, U1 RNA, and five peptides. Calf thymus U1 RNA was found to be identical in sequence to that of man. A sequence of 55 nucleotides within the 165 nucleotide RNA was the minimal RNA fragment found in RNP particles that were still immunologically active. Two of the RNP peptides react with patient sera monospecific for RNP and thus, are presumably the antigenic peptides complexed with the 55 nucleotide RNA sequence.
小核核糖核蛋白复合体是多种自身免疫性疾病中的抗原。针对核糖核蛋白（RNP）抗原的循环抗体高滴度血清学模式是混合性结缔组织病（MCTD）的诊断标志物；而抗Sm抗体在系统性红斑狼疮（SLE）中较为常见。小牛胸腺和兔胸腺都是临床和研究实验室中常用的、制备相应抗原RNP和Sm的优质来源（A.M.博克等人，附文）。因此，对这些制剂中最小抗原决定簇进行生化和结构表征，对于其实验室应用很重要，对于理解MCTD、SLE及其他自身免疫性疾病实例也意义重大。对来自多种不同小牛胸腺提取物制剂的具有免疫活性的RNP进行纯化和生化分析后发现，单特异性MCTD患者血清中的大多数抗体识别的抗原由165个核苷酸的RNA、U1 RNA和五种肽组成。发现小牛胸腺U1 RNA的序列与人的相同。165个核苷酸RNA中的一段55个核苷酸的序列是在仍具有免疫活性的RNP颗粒中发现的最小RNA片段。两种RNP肽与对RNP单特异性的患者血清发生反应，因此，推测它们是与55个核苷酸RNA序列复合的抗原肽。
