Extractable nuclear antigen Ab

Keywords: Extractable nuclear antigen antibody, ENA antibody

Specimen:

5 mL blood in plain tube.

Method:

Electrophoresis, ELISA , line blot.

Reference Interval:

Qualitative test

Application:

Performed when the ANA is positive to determine ANA specificities, some of which identify categories of disease with implications important for treatment and prognosis.

Also indicated when there is a high suspicion of connective tissue disease with negative ANA; antibodies to Ro (SS-A) may not be detected by ANA.

Interpretation:

The presence of antibodies against extractable nuclear antigen is highly suggestive of systemic rheumatic disease.

Defined antigen specificities include:

RNP - mixed Connective tissue diseases;

Sm - highly specific for SLE;

Ro (SS-A) - subacute cutaneous lupus, associated with recurrent abortion, congenital heart block and Sjögren syndrome;

La (SS-B) - Sjögren syndrome;

Scl 70 - Scleroderma;

Jo-1 antibody - Myositis; and

PMSCL antibody – Polymyositis scleroderma overlap.

Reference:

Tan EM et al. Clin Immunol Immunopath 1988; 47: 121-141.

Phan T et al. Clinical and Diagnostic Laboratory Immunology Jan 2002: 1 - 7.