Evaluation of F-actin ELISA for the diagnosis of autoimmune hepatitis.
OBJECTIVE
Antibodies to F-actin have been proposed to increase specificity in the diagnosis of autoimmune hepatitis (AIH). We compared the diagnostic value of a new F-actin enzyme-linked immunosorbent assay (ELISA) with the current gold standard of detection of smooth muscle antibodies by indirect immunofluorescence (SMA-IFT).


METHODS
Archived sera of 47 patients with SMA positive AIH were tested with the F-actin ELISA and SMA-IFT. Prospectively collected sera of 123 patients with various liver diseases, 35 of whom had AIH, were analyzed by both assays. Different cutoff limits were considered for the F-actin ELISA (increments between 20 and 60 ELISA units) and SMA-IFT (titers of 1:40, 1:80, and 1:160).


RESULTS
The F-actin ELISA had a sensitivity of 100% to detect all of 47 SMA positive AIH sera and the value of the ELISA units correlated with that of SMA titers (p < 0.0001). In prospective analysis, F-actin ELISA showed a superior sensitivity (74% vs 34%) and a similar specificity (98% vs 99%) and positive predictive value (88% vs 92%), compared with SMA-IFT. Combining both assays improved neither sensitivity nor specificity.


CONCLUSIONS
The new F-actin ELISA seems to be a useful diagnostic tool with similar specificity and superior sensitivity for the diagnosis of AIH, compared with standard SMA-IFT. Due to its simplicity and operator independency, the F-actin ELISA may become a preferred screening technique for detection of autoantibodies in patients with suspected AIH.
Frenzel
Christian
C
The I. Department of Medicine, University Medical Centre Hamburg-Eppendorf, Hamburg, Germany.
Herkel
Johannes
J
Lüth
Stefan
S
Galle
Peter R
PR
Schramm
Christoph
C
Lohse
Ansgar W
AW
D000199:Actins / Q000276:immunology*; D000328:Adult; D000368:Aged; D001323:Autoantibodies / Q000097:blood*; D004797:Enzyme-Linked Immunosorbent Assay / Q000379:methods*; D005260:Female; D019084:Fluorescent Antibody Technique, Indirect; D019693:Hepatitis, Autoimmune / Q000097:blood / Q000175:diagnosis*; D006801:Humans; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D012372:ROC Curve; D015203:Reproducibility of Results
D000199:Actins; D001323:Autoantibodies