Buyon J P, Slade S G, Reveille J D, Hamel J C, Chan E K
Department of Medicine, New York University School of Medicine, NY.
J Immunol. 1994 Apr 1;152(7):3675-84.
Abs to the 52-kDa SS-A/Ro protein are found in high prevalence in patients with Sjogren's syndrome (SS) and mothers whose children have the neonatal lupus syndrome (NLS). This study further defines the specificity of this response. By ELISA, 97% of 59 mothers of offspring with NLS had Abs to the 52-kDa recombinant protein compared with 80% in 132 non-NLS sera with anti-SS-A/Ro Abs (p < 0.004). Antigenic regions on the 52-kDa protein were evaluated by immunoprecipitation of [35S]-radiolabeled in vitro translation products. Ninety-five percent of 99 sera that contained anti-52-kDa Abs by ELISA reacted with a large fragment spanning amino acids (aa) 1-291. Two antigenic regions were identified, aa169-291 containing the leucine zipper that was recognized by 83% of the anti-52-kDa sera tested and aa1-78 containing the zinc finger domains that was recognized by only half the sera. No sera immunoprecipitated this N-terminal fragment exclusively. Recognition of one or both regions was not unique to any clinical subset of patients; however, a greater number of sera from patients with SS contained both specificities, whereas asymptomatic mothers whose children had NLS comprised the only clinical group in which the majority recognized the central region of the molecule. Reactivity with both epitopes was demonstrated significantly more often in sera with high titers of Abs to the 60-kDa rSS-A/Ro protein by ELISA in association with the anti-52-kDa response compared with anti-52-kDa responses associated with low titers of anti-60-kDa Abs (p < 0.04). Eighty-one percent of 16 sera that recognized the N-terminal epitope were from patients with the combination of HLA-DRB10301, DQA10501, and DQB1*0201 alleles, compared with 30% of 10 that recognized only the central epitope (p < 0.02). In summary, this study demonstrates that there are at least two antigenic determinants on the 52-kDa SS-A/Ro protein, one "immunodominant" and the other recognized by a more "restricted" subset of anti-52-kDa SS-A/Ro Abs.
抗52-kDa SS-A/Ro蛋白抗体在干燥综合征（SS）患者以及子女患有新生儿狼疮综合征（NLS）的母亲中高度流行。本研究进一步明确了这种反应的特异性。通过酶联免疫吸附测定（ELISA），59名NLS患儿的母亲中，97%对抗52-kDa重组蛋白有抗体，而在132份含有抗SS-A/Ro抗体的非NLS血清中，这一比例为80%（p<0.004）。通过对[35S]放射性标记的体外翻译产物进行免疫沉淀，评估了52-kDa蛋白上的抗原区域。ELISA检测显示含有抗52-kDa抗体的99份血清中，95%与一个跨越氨基酸（aa）1 - 291的大片段发生反应。确定了两个抗原区域，aa169 - 291包含亮氨酸拉链，83%检测的抗52-kDa血清可识别该区域，aa1 - 78包含锌指结构域，只有一半的血清可识别该区域。没有血清仅免疫沉淀这个N端片段。对一个或两个区域的识别并非任何临床亚组患者所特有；然而，更多SS患者的血清包含两种特异性，而子女患有NLS的无症状母亲是唯一大多数血清识别分子中央区域的临床组。与低滴度抗60-kDa抗体相关的抗52-kDa反应相比，ELISA检测显示，高滴度抗60-kDa rSS-A/Ro蛋白抗体的血清与抗52-kDa反应同时出现时，与两个表位的反应性显著更常见（p<0.04）。识别N端表位的16份血清中，81%来自具有HLA-DRB1*（0301）、DQA1*（0501）和DQB1*（0201）等位基因组合的患者，而仅识别中央表位的10份血清中这一比例为30%（p<0.02）。总之，本研究表明52-kDa SS-A/Ro蛋白上至少有两个抗原决定簇，一个是“免疫显性”的，另一个被抗52-kDa SS-A/Ro抗体中更“受限”的亚组所识别。
