这些图像是ANA阴性（显微镜下观察）的示例。由于ANA阴性图像会有不同的呈现形式，所以AC-0不能当做绝对的ANA 阴性，只是作为一个对照。为什么会有这么多种可能的变化是由于目前缺乏明确的细胞内结构染色标准，且比较主观并只能做到半定量。我们需要讨论的是如何确定区分ANA阳性和ANA阴性的临界值。目前，普遍的共识认为这个临界值应该通过对部分正常对照人群的实验数据来确定。同时，临界值的确定高度依赖于不同实验室所使用的HEp-2基质，包括因不同制造商和不同批次来源的HEp-2载片本身的差异、荧光染料偶联的二抗试剂、显微镜和相机的设置、血清稀释度以及其他变量。在使用电脑屏幕在线读取AC-0图像时，应注意不同的电脑默认的屏幕亮度设置也是不同的，可能需要做一些调整从而到正确的解读。对于有两个屏幕的电脑来说，其屏幕的亮度也不一定是同步的。这些AC-0的图片用于展示一些细胞的清晰度，包括分裂中期的细胞，如果不能看到足够的细节，则可能是屏幕亮度设置太暗；另一方面，如果这些图片的绿色荧光较强，请考虑是否屏幕亮度设置得太亮。总之，在电脑屏幕上读取这些图像时应该根据情况相应地调整屏幕的亮度设置。值得注意的是，当使用PC/MAC电脑下载并读取这些AC-0图像时，除了上述屏幕亮度设置之外，根据不同的图像读取软件可能还会出现一些其它的变化。

见Herold等人著作查看完整讨论 (Clin Chem Lab Med. 2018;56:1799-802.)

Herold M, Klotz W, Andrade LEC, Conrad K, de Melo Cruvinel W, Damoiseaux J, Fritzler MJ, von Muhlen CA, Satoh M, Chan EKL. International Consensus on Antinuclear Antibody Patterns: defining negative results and reporting unidentified patterns. Clin Chem Lab Med. 2018;56:1799-802.

These images are provided as examples of what are considered as ANA-negative as viewed under a microscope. Since a negative ANA can be represented by a number of different images, it should be clear that AC-0 should not be regarded as the definite example but used for comparison purposes only. The guiding feature that links these variable possibilities is the absence of a clear-cut staining in any given subcellular structure. This definition is both subjective and semi-quantitative at best.

There should be a discussion regarding how ANA-positive vs ANA-negative cut-off is determined. There are general consensus that such cut-offs should be determined experimentally and locally with normal population controls. The cut-off is highly dependent on the HEp-2 substrates used by individual laboratories, including factors specific to HEp-2 slide manufacturers and lot-to-lot variations, fluorochrome conjugated secondary antibody reagents, microscope and camera settings, serum dilutions, and other variables.

In viewing these AC-0 images online using a computer screen, note that the screen default brightness setting may vary from computer to computer and some adjustment may be necessary for appropriate interpretation.  For computer with two screens, the brightness for both screen is not necessary in sync either. These AC-0 images are selected to show some definition of cells, including cells in metaphase. If one cannot see sufficient details, probably the screen brightness is set too dark.  On the other hand, if these images show too much green staining, please consider the screen brightness is set too bright.  In summary, viewers of these images on computer screen should make appropriate adjustment in their screen brightness setting accordingly.

Please note that when these AC-0 images are downloaded and viewing with PC/Mac computers, there may be additional variations depending on the image viewing software, in addition to screen brightness setting as discussed above.

See Herold et al. for full discussion (Clin Chem Lab Med. 2018;56:1799-802.)

Herold M, Klotz W, Andrade LEC, Conrad K, de Melo Cruvinel W, Damoiseaux J, Fritzler MJ, von Muhlen CA, Satoh M, Chan EKL. International Consensus on Antinuclear Antibody Patterns: defining negative results and reporting unidentified patterns. Clin Chem Lab Med. 2018;56:1799-802.