'Actin-reactive' discriminated from 'non-actin-reactive' smooth muscle autoantibody by immunofluorescence reactivity with rat epithelial cell line.
OBJECTIVE
To compare smooth muscle antibody (SMA) patterns in tissue sections with patterns in an immunofluorescence assay (IFA) using a rat intestinal epithelial cell line and results from an F-actin IgG ELISA.


METHODS
SMA positive sera (n = 188) were classified by immunofluorescence staining of rodent kidney, stomach and liver sections as SMA-T (tubules) (n = 124) or SMA-V (vessels) (n = 64). The F-actin pattern on the rat epithelial cell line was identified by immunofluorescence staining of actin cables that was confirmed by dual immunofluorescence co-localisation with phalloidin.


RESULTS
Of 124 SMA-T positive sera, 123 reacted with the epithelial cell line and 120 with F-actin by ELISA, giving sensitivity for detection of anti-F-actin antibody of 99% and 97%, respectively. Of 64 SMA-V positive sera, four reacted with the epithelial cell line (6%) and 41 with F-actin by ELISA (64%). Tests of 493 normal blood donors and 100 disease controls yielded specificities of 584/593 (98.5%) and 562/593 (94.8%) for the cell line IFA and F-actin ELISA, respectively.


CONCLUSIONS
The rat epithelial cell line IFA is a robust diagnostic assay for anti-F-actin antibody that can either replace the routine screening for actin-reactive SMA-T antibody in tissue sections or be used as a confirmatory assay for anti-F-actin antibody after screening by F-actin ELISA or on rodent tissue sections by IFA.
Toh
Ban-Hock
BH
Autoimmunity Laboratory, Centre for Inflammatory Diseases, Department of Medicine, Faculty of Medicine, Monash University, Victoria, Australia. Ban-Hock.Toh@med.monash.edu.au
Taylor
Roberta
R
Pollock
Wendy
W
Dearden
Sharon
S
Gill
Cassandra C
CC
Buchner
Carol
C
Burlingame
Rufus W
RW
D000199:Actins / Q000276:immunology*; D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000818:Animals; D001323:Autoantibodies / Q000097:blood* / Q000276:immunology; D015415:Biomarkers / Q000097:blood; D002460:Cell Line; D002648:Child; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D005455:Fluorescent Antibody Technique / Q000379:methods*; D019693:Hepatitis, Autoimmune / Q000097:blood / Q000175:diagnosis / Q000276:immunology*; D006801:Humans; D007413:Intestinal Mucosa / Q000276:immunology / Q000473:pathology; D008297:Male; D008875:Middle Aged; D009130:Muscle, Smooth / Q000276:immunology* / Q000473:pathology; D011237:Predictive Value of Tests; D051381:Rats; D055815:Young Adult
D000199:Actins; D001323:Autoantibodies; D015415:Biomarkers