Tan E M, Feltkamp T E, Smolen J S, Butcher B, Dawkins R, Fritzler M J, Gordon T, Hardin J A, Kalden J R, Lahita R G, Maini R N, McDougal J S, Rothfield N F, Smeenk R J, Takasaki Y, Wiik A, Wilson M R, Koziol J A
The Scripps Research Institute, La Jolla, California 92037, USA.
Arthritis Rheum. 1997 Sep;40(9):1601-11. doi: 10.1002/art.1780400909.
To determine the range of antinuclear antibodies (ANA) in "healthy" individuals compared with that in patients with systemic lupus erythematosus (SLE), systemic sclerosis (SSc; scleroderma), Sjögren's syndrome (SS), rheumatoid arthritis (RA), or soft tissue rheumatism (STR).
Fifteen international laboratories experienced in performing tests for ANA by indirect immunofluorescence participated in analyzing coded sera from healthy individuals and from patients in the 5 different disease groups described above. Except for the stipulation that HEp-2 cells should be used as substrate, each laboratory used its own in-house methodology so that the data might be expected to reflect the output of a cross-section of worldwide ANA reference laboratories. The sera were analyzed at 4 dilutions: 1:40, 1:80, 1:160, and 1:320.
In healthy individuals, the frequency of ANA did not differ significantly across the 4 age subgroups spanning 20-60 years of age. This putatively normal population was ANA positive in 31.7% of individuals at 1:40 serum dilution, 13.3% at 1:80, 5.0% at 1:160, and 3.3% at 1:320. In comparison with the findings among the disease groups, a low cutoff point at 1:40 serum dilution (high sensitivity, low specificity) could have diagnostic value, since it would classify virtually all patients with SLE, SSc, or SS as ANA positive. Conversely, a high positive cutoff at 1:160 serum dilution (high specificity, low sensitivity) would be useful to confirm the presence of disease in only a portion of cases, but would be likely to exclude 95% of normal individuals.
It is recommended that laboratories performing immunofluorescent ANA tests should report results at both the 1:40 and 1:160 dilutions, and should supply information on the percentage of normal individuals who are positive at these dilutions. A low-titer ANA is not necessarily insignificant and might depend on at least 4 specific factors. ANA assays can be a useful discriminant in recognizing certain disease conditions, but can create misunderstanding when the limitations are not fully appreciated.
确定“健康”个体中抗核抗体（ANA）的范围，并与系统性红斑狼疮（SLE）、系统性硬化症（SSc；硬皮病）、干燥综合征（SS）、类风湿关节炎（RA）或软组织风湿病（STR）患者中的ANA范围进行比较。
15个通过间接免疫荧光法进行ANA检测的国际实验室参与分析来自健康个体以及上述5个不同疾病组患者的编码血清。除规定应使用HEp-2细胞作为底物外，每个实验室使用其自己的内部方法，以便数据有望反映全球ANA参考实验室的横断面输出。血清在4种稀释度下进行分析：1:40、1:80、1:160和1:320。
在健康个体中，20至60岁的4个年龄亚组中ANA的频率无显著差异。在血清稀释度为1:40时，这个假定的正常人群中31.7%的个体ANA呈阳性，1:80时为13.3%，1:160时为5.0%，1:320时为3.3%。与疾病组的结果相比，血清稀释度为1:40时的低截断点（高敏感性，低特异性）可能具有诊断价值，因为它几乎会将所有SLE、SSc或SS患者分类为ANA阳性。相反，血清稀释度为1:160时的高阳性截断点（高特异性，低敏感性）仅在部分病例中有助于确认疾病的存在，但可能会排除95%的正常个体。
建议进行免疫荧光ANA检测的实验室应报告1:40和1:160稀释度时的结果，并应提供在这些稀释度下呈阳性的正常个体的百分比信息。低滴度ANA不一定无意义，可能至少取决于4个特定因素。ANA检测在识别某些疾病状况时可能是一种有用的判别方法，但如果没有充分认识到其局限性，可能会产生误解。
