Autoantibodies to alpha-fodrin in primary Sjögren's syndrome and SLE detected by an in vitro transcription and translation assay.
OBJECTIVE
To investigate the prevalence of alpha-fodrin autoantibodies in primary Sjögren's syndrome (SS) and systemic lupus erythematosus (SLE) with and without secondary SS, using an in vitro transcription and translation assay (ITT).


METHODS
cDNA encoding JS-1, the amino-terminal portion of alpha-fodrin, was used for ITT. Immunoprecipitation was performed with sera from 56 primary SS patients and 67 SLE patients, 14 with and 53 without secondary SS. Correlations to RF, ANA, anti-dsDNA, anti-SS-A and anti-SS-B antibodies, hypergammaglobulinemia, labial salivary gland biopsy grade, extraglandular manifestations and a modified SLE disease activity index (mSLEDAI) were made.


RESULTS
Autoantibodies against alpha-fodrin were detected in 16/56 (29%) of primary SS patients and in 25/53 (47%) of sera from SLE patients without secondary SS. In SLE patients with secondary SS the prevalence was 3/14 (21%). None of the blood donors showed alpha-fodrin reactivity. Correlations were found to RF, ANA, anti-dsDNA antibodies and a positive mSLEDAI score.


CONCLUSIONS
The frequency of alpha-fodrin autoantibodies detected by this method is similar in sera from primary SS patients and SLE patients with or without secondary SS. The presence of alpha-fodrin autoantibodies seems to reflect non-organ-specific autoimmunity in primary SS and SLE and to be of limited discriminating value.
Nordmark
G
G
Section of Rheumatology, Centre for Laboratory Medicine, University Hospital, Uppsala, Sweden. Gunnel.Nordmark@medsci.uu.se
Rorsman
F
F
Rönnblom
L
L
Cajander
S
S
Taussig
M J
MJ
Kämpe
O
O
Winqvist
O
O
D001323:Autoantibodies / Q000032:analysis*; D001681:Biological Assay; D015415:Biomarkers / Q000032:analysis; D002352:Carrier Proteins / Q000235:genetics / Q000276:immunology*; D002460:Cell Line; D018076:DNA, Complementary / Q000032:analysis; D005260:Female; D006801:Humans; D066298:In Vitro Techniques; D008180:Lupus Erythematosus, Systemic / Q000097:blood / Q000276:immunology* / Q000503:physiopathology; D008297:Male; D008840:Microfilament Proteins / Q000235:genetics / Q000276:immunology*; D008875:Middle Aged; D011233:Precipitin Tests; D014176:Protein Biosynthesis; D012217:Rheumatoid Factor / Q000097:blood; D012720:Severity of Illness Index; D012859:Sjogren's Syndrome / Q000097:blood / Q000276:immunology* / Q000503:physiopathology; D014158:Transcription, Genetic; D013049:Spectrin
D001323:Autoantibodies; D015415:Biomarkers; D002352:Carrier Proteins; D018076:DNA, Complementary; D008840:Microfilament Proteins; D012217:Rheumatoid Factor; D013049:Spectrin