Smith antibodies (anti-Sm)

Detection of Smith antibodies, or anti-Sm, is very specific (99%) for systemic lupus erythematosus (SLE), thus regarded as a diagnostic marker for SLE. Detection of these autoantibodies is one of the ACR criteria for the diagnosis of SLE. However, a negative result does not rule out SLE.

There seems to be a relationship between the anti-Sm antibodies and severe organ manifestation of the disease (e.g. involvement of the CNS and/or kidney) and vascular skin and mucosal manifestations and the presence of antibodies against double-stranded DNA (dsDNA). Therefore anti-Sm is also regarded as a prognostic marker for lupus.

The anti-Sm antibody is part of the extractable nuclear antigen antibodies (ENA) panel, which is usually ordered following a positive antinuclear antibodies (ANA) test in people showing clinical signs of an autoimmune disease.

Evidence of anti-Sm antibodies can be provided by means of indirect immunofluorescence assays (IFA), by enzyme-linked immunosorbant assay (ELISA), or by line immunoassays (immunoblots). In indirect immunofluorescence assays on HEp-2 cells the interphase nuclei demonstrate a coarse granular pattern, whereas mitotic cells are negative.

 

Tests offered by ORGENTEC Diagnostika

ELISA/Alegria®:

Anti-Sm (ORG 510, ORG 210)
ENA-4-Profile (ORG 544)
ENA-6-Profile (ORG 546)
ENAcombi (ORG 514)

Immunoblot:

ANA-9-Line (ORG 710-08, ORG 710-16)
Nucleo-9-Line (ORG 711-08, ORG 711-16)

IFA:

Anti-Nuclear Antibodies HEp-2 (ANA-HEp-2) (ORG 870)

 

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