Anti-nuclear antibody

Background

Refers to antibodies that react to nuclear proteins
General screen, sometimes followed by assessing for specific antibodies
- Antigens that are insoluble in saline: double-stranded DNA, deoxyribonucleoprotein (DNP), histones
- Antigens that are soluble in saline (or extracted; ENA): anti-Smith, anti-RNP, anti-Ro/La, anti-Scl-70
May be measured by indirect immunofluorescence assay (IIF) (the gold standard), enzyme-linked immunosorbent assay (EIA), or other technologies

Healthy people can have a 1:40 titre (25 to 45% of health people), 1:80 titre (10 to 15%), or even 1:160 titre (5%)
- Increases with age
Systemic lupus erythematosus
- ANA assay was essentially developed as a screening tool for SLE
- It is 90 to 95% sensitive

Disease	% Positive	Titre	Common Patterns
SLE (active)	95	high	homogeneous > speckled > rim
SLE (in remission)	90	moderate-high	homogeneous > speckled
MCTD	93	high	speckled > nucleolar
Systemic sclerosis or CREST	85	high	speckled > centromere > nucleolar
Sjögren syndrome	48	moderate-high	speckled > homogeneous
Dermatomyositis/Polymyositis	61	low-moderate	speckled > nucleolar
Rheumatoid arthritis	41	low-moderate	speckled
Drug-induced lupus	95	low-moderate	homogeneous > speckled
Pauciarticular JIA	71	low-moderate	speckled
Graves disease	50	low-moderate	speckled
Hashimoto thyroiditis	46	low-moderate	speckled
Autoimmune hepatitis	63–91	low-moderate	speckled
Primary biliary cirrhosis	10–40	low-moderate	speckled