Targoff I N, Reichlin M
J Immunol. 1987 May 1;138(9):2874-82.
Antibody to the Jo-1 antigen (histidyl-tRNA synthetase) is found almost exclusively in myositis patients, usually those with adult PM, but has been found in only 30% of that group by immunodiffusion or other techniques thus far reported. We have reexamined the prevalence of antibody to Jo-1 in sera from 130 patients and 82 controls by using the sensitive ELISA technique. The ELISA used affinity-purified, enzymatically active bovine Jo-1 antigen. A wide range of antibody level by ELISA was found among 24 immunodiffusion positive sera. Six myositis and two control sera had apparent specific antibody detectable only by ELISA. Overall, however, the antibody continued to show high myositis specificity with predominance in adult PM (35.8% in that group). Because the antibody inhibits enzymatic activity of the synthetase antigen, we also studied the quantitative inhibitory activity of these sera to compare with the antibody activity as determined by ELISA. Twenty-four immunodiffusion-positive sera, 29 immunodiffusion-negative sera, and 15 normal sera were tested at 1/50 dilution in the reaction mixture. There was background inhibition by all normal sera tested that averaged 30.5%. All but one immunodiffusion negative myositis sera (a high binder by ELISA) inhibited less than 50% of the average with normal serum. Twenty-three of 24 immunodiffusion positive sera inhibited greater than 80% of this normal average; the other inhibited 66%. The serum dilution giving 50% inhibition was highly correlated (R = 0.83) with the ELISA activity. Thus, inhibition of histidyl-tRNA synthetase activity is a relatively accurate measure of Jo-1 antibody. This method should be applicable to measuring antibody to other aminoacyl-tRNA synthetases.
抗Jo-1抗原（组氨酰-tRNA合成酶）抗体几乎仅在肌炎患者中发现，通常见于成年多发性肌炎患者，但据目前报道，通过免疫扩散或其他技术，在该组患者中仅30%检测到该抗体。我们采用灵敏的酶联免疫吸附测定（ELISA）技术，重新检测了130例患者和82例对照血清中抗Jo-1抗体的流行情况。该ELISA使用亲和纯化的、具有酶活性的牛Jo-1抗原。在24份免疫扩散阳性血清中，通过ELISA检测到抗体水平差异很大。6份肌炎血清和2份对照血清仅通过ELISA可检测到明显的特异性抗体。然而，总体而言，该抗体仍显示出较高的肌炎特异性，在成年多发性肌炎中占优势（该组中为35.8%）。由于该抗体抑制合成酶抗原的酶活性，我们还研究了这些血清的定量抑制活性，以与ELISA测定的抗体活性进行比较。在反应混合物中，对24份免疫扩散阳性血清、29份免疫扩散阴性血清和15份正常血清进行1/50稀释检测。所有检测的正常血清均有背景抑制，平均为30.5%。除一份免疫扩散阴性的肌炎血清（ELISA检测为高结合者）外，所有免疫扩散阴性的肌炎血清抑制率均低于正常血清平均抑制率的50%。24份免疫扩散阳性血清中有23份抑制率大于正常平均抑制率的80%；另一份抑制率为66%。产生50%抑制的血清稀释度与ELISA活性高度相关（R = 0.83）。因此，组氨酰-tRNA合成酶活性的抑制是抗Jo-1抗体的相对准确指标。该方法应适用于检测针对其他氨酰-tRNA合成酶的抗体。
