Methods of choice for diagnostic antinuclear antibody (ANA) screening: benefit of adding antigen-specific assays to immunofluorescence microscopy.
OBJECTIVE
To evaluate and compare the performances of three enzyme-immunoassays (EIAs) and a double radial immunodiffusion (DRID) test in addition to immunofluorescence (IF) microscopy for routine laboratory screening of patient sera sent for antinuclear antibody (ANA) analysis.


METHODS
3079 consecutive patient sera sent for routine testing of ANA were analysed by IF microscopy on HEp-2 cells (IF-ANA), three different ANA-EIAs, and a DRID test for antibodies against extractable nuclear antigens. The IF-ANA and DRID tests were regarded as reference methods.


RESULTS
By IF-ANA and/or DRID, 375 sera (12%) turned out ANA-positive. A further 171 sera (6%) were positive by EIA, but could not be confirmed either by IF microscopy or DRID. 32 of the 375 ANA-positive (9%) sera were negative by IF microscopy, but had precipitating antibodies against Ro/SS-A (52 and/or 60 kD).


CONCLUSIONS
Different assays for ANA analysis give overlapping results to a certain extent, but are by no means interchangeable. Thus, different ANA tests reflect different aspects of these autoantibodies. The diagnostic utility of ANA testing still mainly refers to IF-microscopy and precipitin tests. IF-ANA should not be abandoned as the golden standard in clinical routine, until diagnostic and classification criteria for systemic lupus erythematosus and other systemic inflammatory autoimmune diseases have been revised. However, in addition we strongly advocate that a specific test for anti-Ro/SS-A antibodies is always included.
Dahle
Charlotte
C
Division of Clinical Immunology, Department of Molecular and Clinical Medicine/AIR, Faculty of Health Sciences, Linköping University Hospital, SE-581 85 Linköping, Sweden. lotta.dahle@lio.se
Skogh
Thomas
T
Aberg
A K
AK
Jalal
A
A
Olcén
P
P
D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000974:Antibodies, Antinuclear / Q000097:blood / Q000276:immunology*; D002648:Child; D002675:Child, Preschool; D005260:Female; D005455:Fluorescent Antibody Technique / Q000379:methods; D006801:Humans; D007223:Infant; D008180:Lupus Erythematosus, Systemic / Q000175:diagnosis* / Q000276:immunology; D008297:Male; D008875:Middle Aged; D044967:Serum / Q000276:immunology
D000974:Antibodies, Antinuclear; C035356:SS-A antibodies