This is an example of a cell cycle-dependent speckled ANA pattern called proliferating cell nuclear antigen (PCNA).
With this pattern, the antigen that the antibodies are directed to is only expressed during a limited portion of the cell's growth cycle. During other parts of the growth cycle, the antigen is not expressed. This creates a pattern where only 30-50% of the cells stain positive. The speckled staining within these positive cells varies between coarse speckled (a) and smooth speckled (b). Cells not expressing the antigen are negative (c).
Follow-up testing to confirm antibodies to PCNA is recommended. Anti-PCNA antibodies are specific for SLE.
This pattern is reported as "ANA positive, Speckled, possible PCNA; titering is necessary."
Proliferating Cell Nuclear Antigen (PCNA) cell cycle-dependent pattern:
Antigen is not expressed in all growth stages.
Interphase cells:
- 30-50% of interphase cells stain
- Coarse to fine speckling in the nucleus
- Nucleoli do not stain
Metaphase mitotic cells:
- No staining at this stage of the cell cycle
