Detection of autoantibodies to ss-a/ro by indirect immunofluorescence using a transfected and overexpressed human 60 kd ro autoantigen in hep-2 cells

✍ Scribed by Dr. Marvin J. Fritzler; B. Joan Miller

• Publisher: John Wiley and Sons
• Year: 1995
• Tongue: English
• Weight: 845 KB
• Volume: 9
• Category: Article
• ISSN: 0887-8013
• DOI: 10.1002/jcla.1860090312

✦ Synopsis

The objective of the study was to determine the sensitivity and specificity of an indirect immunofluorescence (IIF) assay using transfected HEp-2 cells to detect anti-SS-A/ Ro autoantibodies in human sera. Seventythree sera having SS-NRo autoantibodies as determined by double immunodiffusion (ID) and immunoblotting ( 16) were tested by IIF on a HEp-2 cell substrate that had been transfected with a full-length cDNA encoding a human 60 kD SS-NRo autoantigen. Controls included 30 normal human sera and 50 sera with a variety of other antinuclear antibodies. Prototype human and rabbit sera directed against the 60 kD SS-NRo antigen produced intense speckled nuclear and nucleolar staining of transfected cells. Sixtynine of 73 (95%) SS-NRo positive sera also produced this characteristic staining pattern. The endpoint autoantibody titers on trans-fected cells was fivefold greater than on untransfected cells. The 30 normal human sera and the 50 sera with other antinuclear antibodies did not produce this characteristic staining. Six of 32 (1 9%) unselected sera that were sent for autoantibody testing had reactivity with transfectants by IIF. Four of the six sera were confirmed to have anti-SS-NRo antibodies by ID and 516 by IB. By contrast, only three of these sera were scored as having a staining pattern compatible with SS-NRo antibodies by IIF on standard HEp-2 substrates. We conclude that SS-NRo autoantibodies can be detected by an IIF assay using a HEp-2 cell substrate transfected with a SS-NRo cDNA. This new substrate detects SS-NRo antibodies that were not identified on standard HEp-2 substrates and by other immunoassays.