F-actin reactive smooth muscle antibody in subjects with normal liver function.
OBJECTIVE
Smooth muscle antibody (SMA) with F-actin reactivity has been reported as a diagnostic marker of autoimmune hepatitis. We re-visited this relationship by randomly selecting SMA-positive sera to test for reactivity with F-actin by ELISA. We correlated such reactivity with liver function tests.


METHODS
Sera positive for SMA by indirect immunofluorescence were tested for reactivity by F-actin ELISA and the results correlated with liver function tests.


RESULTS
89 SMA-positive sera reacted with F-actin by ELISA. Of these, 35 (39%) had normal liver enzymes, while 54 (60%) had elevated liver enzymes. There was no difference between the groups with respect to age at presentation, female preponderance or presence of anti-nuclear antibody. In both groups, high titre SMA antibody predominantly with immunofluorescence staining of renal glomeruli and peritubular fibrils of renal tubules ('G/T' subset) correlated with makedly elevated F-actin values by ELISA. 'Actin cables' by immunofluorescence staining of Hep-2 cells were infrequently found in both groups.


CONCLUSIONS
This is the first report of SMA with F-actin reactivity in subjects with normal liver function.
Toh
Ban-Hock
BH
Immunology Laboratory, Gribbles Pathology, Healthscope, Clayton, Victoria, Australia. ban-hock.toh@med.monash.edu.au
Taylor
Roberta
R
Pollock
Wendy
W
D000199:Actins / Q000276:immunology*; D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001323:Autoantibodies / Q000097:blood*; D015415:Biomarkers / Q000097:blood; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D019084:Fluorescent Antibody Technique, Indirect; D019693:Hepatitis, Autoimmune / Q000097:blood / Q000175:diagnosis; D006801:Humans; D008111:Liver Function Tests; D008297:Male; D008875:Middle Aged; D009130:Muscle, Smooth / Q000276:immunology*; D000637:Transaminases / Q000097:blood; D055815:Young Adult
D000199:Actins; D001323:Autoantibodies; D015415:Biomarkers; D000637:Transaminases