This is an example of the SS-A/Ro ANA pattern using the HEp-2000® substrate. (This hyperexpression pattern is not seen on standard HEp-2 substrates.)
As stated earlier, the HEp-2000® substrate utilizes genetically engineered HEp-2 cells with increased expression of SS-A/Ro antigen in the cells.
When the patient sample contains autoantibodies to the SS-A/Ro antigen, approximately 90% of the time the sample will produce a distinctive pattern with 10-15% of the hyperexpression cells showing strong speckled staining, frequently with strong nucleolar staining (a). The metaphase mitotic cells are negative (b). The remaining cells demonstrate weak speckled and nucleolar staining (c).
The presence of anti-SS-A/Ro antibodies is confirmed by the unique staining pattern. Follow-up testing for antibodies to other extractable nuclear antigens (ENAs) is recommended. These antibodies are seen in patients with SLE, Sjögren's syndrome, and are low frequency in other diseases.
This pattern is reported as "ANA positive, SS-A/Ro pattern, anti-SS-A/Ro antibodies present." Most labs will titer these samples. However, because the significance is that the anti-SS-A antibodies are present regardless of the titer endpoint, some labs do not titer the SS-A/Ro pattern.
SS-A/Ro (HEp-2000® only) Interphase:
Seen with about 89% of samples containing anti-SS-A/Ro antibodies
Hyperexpressing interphase cells
- 10-15% hyperexpress SS-A/Ro antigen
- Stronger nucleolar staining
- Stronger speckled staining
Non-hyperexpressing interphase cells
SS-A/Ro (HEp-2000® only) Metaphase:
Metaphase mitotic cells
- No staining in the chromosome region
- Region outside of the chromosome area will stain with variable intensity
Some mitotics may also demonstrate brighter staining.
