Antinuclear antibodies

Result from dysregulation of the immune system leading to the formation of auto antibodies against a variety of cellular and nuclear antigens.

Most common method to test for ANA are indirect immunoflorescence assay an enzyme-linked Immunosorbent assay (ELISA).

Indirect immunofluorescence assay has a higher sensitivity then ELISA for patients with systemic lupus erythematosus.

Indirect immunofluorescence assay is the time intensive and requires significant technical expertise.

Sensitivity of various ELISA tests ranges from 69-97% with specificity between 81-97% for diagnosing SLE.

Normal titer less than 1:20 dilution.

May be positive in normal patients without an underlying abnormality in 3-30% of patients, particularly in older women.

At least 20% of healthy women are known to have a positive ANA screening test.

ANA is a non specific test and maybe positive in healthy individuals and patients with autoimmune thyroid diseases, idiopathic thrombocytopenic purpura, infectious states, and multiple sclerosis.

Present in as many as 45% of patients with autoimmune thyroid disease.

Seen in rheumatologic disease such as systemic lupus erythematosus, rheumatoid arthritis, mixed connective disease, Sjogren’s syndrome and narcotizing vasculitis.

May be seen with infections including tuberculosis, chronic active hepatitis, subacute bacterial endocarditis, and HIV.

May be seen with type I diabetes, multiple sclerosis, silicone gel implants, pregnancy, elderly and with pulmonary fibrosis.

Estimated prevalence of ANA in individuals 12 years and older is 13.8%

Medications associated with positive test: carbamazepine, chlorpromazine, ethosuximide, gold salts, griseofulvin, hydralazine, isoniazid, methyldopa, minocycline penicillamine, phenytoin, procainamide, primidone, quinidine, and thiazides.

Antibodies to double-stranded DNA is highly associated with lupus nephritis.

Associated with systemic lupus, Sjogren’s syndrome, progressive systemic sclerosis, mixed connective-tissue disease, drug-induced lupus, viral hepatitis, HIV, autoimmune thyroid disease and autoimmune hepatitis.

Antinuclear antibody (ANA) related to IgG or IgM antibody.

SLE staining includes rim and homogenous patterns.

CREST syndrome and scleroderma include ANA nucleolar and Centromere patterns.

Anti-centromere antibodies highly specific for limited scleroderma, the CREST syndrome.

Nonspecific patterns include ANA speckled and Diffuse patterns.

Anti-dsDNA has a SLE sensitivity of 60%.

Anti-dsDNA specific for SLE.

Anti-dsDNA associated with lupus nephritis.

Anti-dsDNA associated with CNS lupus.

Anti-Smith or Anti-Sm lupus sensitivity of 20-30% and is highly specific with lupus erythematosus.

Anti-ribosomal P has a lupus sensitivity of 20-30% and is highly specific for lupus erythematosus and is associated with lupus psychosis.

RNP associated with Mixed connective tissue disease up to 95%, SLE 30 to 50% polymyositis and/or dermatomyositis 20%.

Anti-Jo1 has a sensitivity for poliomyelitis and dermatomyositis of 30%, associated with Raynaud’s phenomenon and pulmonary fibrosis.

Antihistone antibodies reflect drug induced SLE with a sensitivity of 90%, and a sensitivity of SLE of 50%.

Anti-Ro (Anti-SSA) have a sensitivity of 75% for Sjogren’s syndrome and a sensitivity for SLE of 40%.

Anti-La (Anti-SSB) has a sensitivity of 40% for Sjogren’s syndrome and a SLE sensitivity of 10-15%.

SS-B/La is an extractable nuclear antigen (ENA) composed of a 48-kD protein combined with RNA species.

SS-B/La antibodies are found primarily in patients with Sjogren syndrome or lupus erythematosus (LE), where they occur with frequencies of approximately 60% and 15%, respectively.

SS-B/La antibodies occur only infrequently in the absence of SS-A/Ro antibodies.

SS-B/La is 1 of 4 autoantigens commonly ref2242ed to as extractable nuclear antigens (ENAs).

Testing for SS-B/La antibodies is not useful in patients without demonstrable antinuclear antibodies.

Anti-ssDNA is a non-specific test and rarely indicated.

Centromere B antibodies seen in Scleroderma-Crest variant.

Scl-70 (anti topisomerase) Scleroderma 20-30%, CREST 13%.

Antiphospholipid antibodies are present with SLE or with other autoimmune diseases who may have manifestations or the antiphospholipid syndrome.

ANCA present in 60-90% of patients with granulomatosis with polyangiitis.

Leave a Reply

Your email address will not be published. Required fields are marked *