Gaither K K, Fox O F, Yamagata H, Mamula M J, Reichlin M, Harley J B
J Clin Invest. 1987 Mar;79(3):841-6. doi: 10.1172/JCI112892.
We have applied a sensitive assay to analyze lupus and Sjögren's syndrome autoantibodies in 40 normal sera. Seven of these bound Ro/Sjögren's syndrome A antigen (SSA). Although this binding was 1,000-fold lower than the highest anti-Ro/SSA level measured from patients, it was inhibited by human Ro/SSA. Positive normal serum-bound Ro/SSA in Western immunoblots and binding activity was demonstrated in the F(ab')2 fragment of IgG. Affinity purification of normal anti-Ro/SSA IgG increased the specific anti-Ro/SSA binding by greater than 17-fold. This purified antibody formed a Ro/SSA precipitin and had a relative affinity for Ro/SSA identical to that of Ro/SSA precipitin-positive patients. These data demonstrate that the anti-Ro/SSA present in healthy normal donors is true autoantibody. Anti-La/Sjögren's syndrome B antigen (SSB) autoantibodies were found in 3 of the 40 normal sera, while none bound nuclear ribonucleoprotein (Sm). Finding low levels of anti-Ro/SSA and anti-La/SSB among normals may indicate that anti-Ro/SSA and anti-La/SSB occur in disease by enhancement of a preexisting immune response.
我们应用一种灵敏的检测方法分析了40份正常血清中的狼疮和干燥综合征自身抗体。其中7份与Ro/干燥综合征A抗原（SSA）结合。尽管这种结合比从患者中测得的最高抗Ro/SSA水平低1000倍，但它可被人Ro/SSA抑制。在Western免疫印迹中，正常血清结合的Ro/SSA呈阳性，并且在IgG的F(ab')2片段中显示出结合活性。对正常抗Ro/SSA IgG进行亲和纯化后，特异性抗Ro/SSA结合增加了17倍以上。这种纯化的抗体形成了Ro/SSA沉淀素，并且对Ro/SSA的相对亲和力与Ro/SSA沉淀素阳性患者的相同。这些数据表明，健康正常供体中存在的抗Ro/SSA是真正的自身抗体。在40份正常血清中的3份中发现了抗La/干燥综合征B抗原（SSB）自身抗体，而没有一份与核核糖核蛋白（Sm）结合。在正常人中发现低水平的抗Ro/SSA和抗La/SSB可能表明，抗Ro/SSA和抗La/SSB在疾病中是通过增强预先存在的免疫反应而产生的。
