Després N, Boire G, Lopez-Longo F J, Ménard H A
Rheumatic Diseases Unit, Faculté de médecine, Université de Sherbrooke, PQ, Canada.
J Rheumatol. 1994 Jun;21(6):1027-33.
To describe a novel autoimmune system (Sa/anti-Sa) specific for rheumatoid arthritis (RA).
Antibodies were detected in immunoblots using human spleen and placenta extracts as antigens. Sera from 482 patients with various rheumatic diseases as well as from healthy controls were evaluated to define the disease associations of anti-Sa antibodies.
Sera from 88 of 206 (42.7%) unselected patients with RA recognized specific protein bands (the Sa antigen) in immunoblots of spleen or placenta extracts, including 9 of 31 (29%) patients seen in the first few months after disease onset. Anti-Sa antibodies were found both in rheumatoid factor (RF) negative (17/63 or 27%) and in RF positive patients with RA (71/143 or 50%). They were nevertheless absent in RF positive patients with other connective tissue diseases (0/39). Antibodies to Sa were essentially found in sera from patients with RA (specificity 98.9%) being found only in 3 patients whose arthritides did not fulfill the ACR criteria. The positive predictive value of anti-Sa antibodies for RA was 96.7%, while its negative predictive value was 69.8%. Anti-Sa antibodies were predominantly of the IgG isotype, with titers varying from 1/50 to > 1/1000. The Sa antigen was characterized as a poorly soluble protein that is present in normal human tissues and that is distinct from all previously described RA associated autoimmune systems.
Anti-Sa antibodies are a novel serological marker highly specific for RA. Since anti-Sa antibodies occur independently of RF, they can be used as an additional diagnostic tool. The molecular nature of the Sa antigen as well as its potential pathogenic role in a significant proportion of patients with chronic articular inflammation of the rheumatoid variety merit further definition.
描述一种针对类风湿关节炎（RA）的新型自身免疫系统（Sa/抗-Sa）。
以人脾和胎盘提取物为抗原，通过免疫印迹法检测抗体。对482例患有各种风湿性疾病的患者以及健康对照者的血清进行评估，以确定抗-Sa抗体与疾病的关联。
在206例未经选择的RA患者中，有88例（42.7%）的血清在脾或胎盘提取物的免疫印迹中识别出特定蛋白条带（Sa抗原），其中包括疾病发作后头几个月内就诊的31例患者中的9例（29%）。抗-Sa抗体在类风湿因子（RF）阴性的RA患者（17/63或27%）和RF阳性的RA患者（71/143或50%）中均有发现。然而，在患有其他结缔组织疾病的RF阳性患者中未发现（0/39）。抗-Sa抗体主要存在于RA患者的血清中（特异性98.9%），仅在3例不符合美国风湿病学会（ACR）标准的关节炎患者中发现。抗-Sa抗体对RA的阳性预测值为96.7%，而其阴性预测值为69.8%。抗-Sa抗体主要为IgG同种型，滴度从1/50到>1/1000不等。Sa抗原的特征是一种难溶性蛋白，存在于正常人体组织中，且与所有先前描述的与RA相关的自身免疫系统不同。
抗-Sa抗体是一种对RA高度特异的新型血清学标志物。由于抗-Sa抗体独立于RF出现，它们可作为一种额外的诊断工具。Sa抗原的分子性质及其在相当一部分类风湿性慢性关节炎症患者中的潜在致病作用值得进一步明确。
