The ANA blot is a confirmatory test following a positive ANA screening.

It identifies antibodies against 18 specific nuclear antigens, providing detailed information about autoimmune disease patterns.

Clinical uses include:

Differentiating between various autoimmune diseases.

Supporting diagnosis of SLE, Sjögren’s syndrome, systemic sclerosis, polymyositis, dermatomyositis, and mixed connective tissue disease.

Monitoring disease progression and treatment response.

The test is performed using a blood sample (serum).

Analyte: Autoantibodies against 18 nuclear antigens in serum.

Antigens Included:

dsDNA

Sm (Smith)

RNP

SSA (Ro)

SSB (La)

Scl-70

Jo-1

Centromere

Histone

Ribosomal P

PCNA

Nucleosome

Mi-2

Ku

PM-Scl

Fibrillarin

RNA Polymerase III

Others depending on kit manufacturer

Normal Result: Negative (no autoantibodies detected).

Positive Result: Presence of specific autoantibodies → indicates autoimmune disease.

Clinical Use:

Provides detailed antibody profile for autoimmune diagnosis.

Helps distinguish overlapping syndromes.

Guides further confirmatory tests and clinical management.