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Proliferating Cell Nuclear Antigen (PCNA)

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 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