Abstract
BACKGROUND: Ro/SS-A autoantibodies associated with systemic lupus erythematosus (SLE) and Sjögren syndrome may be missed during routine screening for antinuclear autoantibodies (ANA) by immunofluorescence using HEp-2 cells. AIMS: To investigate the use of HEp-2 cells transfected with human 60 kDa Ro/SS-A for routine detection of these antibodies. METHODS: 10,500 sera were screened at a dilution of 1:200 for Ro/SS-A antibodies, identified by intense immunofluorescence staining in 10-15% of hyperexpressing cells of either the nucleus and nucleolus combined or the nucleus alone. RESULTS: Ro/SS-A antibodies were identified in 160/2100 ANA positive sera (8%), of which seven were ANA negative (titre < 200) and 33 had weak ANA titres (200) in 85-90% of non-hyperexpressing "background" cells. Enzyme linked immunosorbent assay (ELISA) confirmed the presence of Ro/SS-A antibodies in 110 newly diagnosed Ro/SS-A positive sera. Of these, 50 reacted with Ro/SS-A, 51 with Ro/SS-A and La/SS-B, and nine with Ro/SS-A and other extractable nuclear antigen (ENA) specificities. Fifteen sera which did not show Ro/SS-A antibodies by immunofluorescence tested positive for Ro/SS-A by immunodiffusion, counter-immunoelectrophesis, or ELISA; of these, 14 had ANA titres > 200. Clinical data from 95 Ro/SS-A positive patients showed that 52% had SLE, 24% Sjögren syndrome, 8% rheumatoid arthritis, and 16% other diseases. CONCLUSIONS: (1) HEp-2 cells transfected with human 60 kDa Ro/SSA are useful for routine immunofluorescence detection for Ro/SS-A antibodies with a positive predictive value of 100%; (2) sera positive for Ro/SS-A antibodies by immunofluorescence should be tested for ENA by other methods because > 50% of these sera will have another ENA reactivity in addition to Ro/SS-A; (3) detection of Ro/SS-A by immunofluorescence may be missed in the presence of high titre ANAs; (4) with a detection sensitivity of 91%, a negative immunofluorescence results for Ro/SS-A does not exclude the presence of this autoantibody.
Full text
PDF
Images in this article
Selected References
These references are in PubMed. This may not be the complete list of references from this article.
- ANDERSON J. R., GRAY K. G., BECK J. S., BUCHANAN W. W., McELHINNEY A. J. Precipitating auto-antibodies in the connective tissue diseases. Ann Rheum Dis. 1962 Dec;21:360–369. doi: 10.1136/ard.21.4.360. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Clark G., Reichlin M., Tomasi T. B., Jr Characterization of a soluble cytoplasmic antigen reactive with sera from patients with systemic lupus erythmatosus. J Immunol. 1969 Jan;102(1):117–122. [PubMed] [Google Scholar]
- Gaither K. K., Fox O. F., Yamagata H., Mamula M. J., Reichlin M., Harley J. B. Implications of anti-Ro/Sjögren's syndrome A antigen autoantibody in normal sera for autoimmunity. J Clin Invest. 1987 Mar;79(3):841–846. doi: 10.1172/JCI112892. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Itoh Y., Reichlin M. Autoantibodies to the Ro/SSA antigen are conformation dependent. I: Anti-60 kD antibodies are mainly directed to the native protein; anti-52 kD antibodies are mainly directed to the denatured protein. Autoimmunity. 1992;14(1):57–65. doi: 10.3109/08916939309077357. [DOI] [PubMed] [Google Scholar]
- Keech C. L., Howarth S., Coates T., Rischmueller M., McCluskey J., Gordon T. P. Rapid and sensitive detection of anti-Ro (SS-A) antibodies by indirect immunofluorescence of 60kDa Ro HEp-2 transfectants. Pathology. 1996 Jan;28(1):54–57. doi: 10.1080/00313029600169533. [DOI] [PubMed] [Google Scholar]
- Keech C. L., McCluskey J., Gordon T. P. Transfection and overexpression of the human 60-kDa Ro/SS-A autoantigen in HEp-2 cells. Clin Immunol Immunopathol. 1994 Oct;73(1):146–151. doi: 10.1006/clin.1994.1181. [DOI] [PubMed] [Google Scholar]
- Manoussakis M. N., Kistis K. G., Liu X., Aidinis V., Guialis A., Moutsopoulos H. M. Detection of anti-Ro(SSA) antibodies in autoimmune diseases: comparison of five methods. Br J Rheumatol. 1993 Jun;32(6):449–455. doi: 10.1093/rheumatology/32.6.449. [DOI] [PubMed] [Google Scholar]
- Tan E. M. Antinuclear antibodies: diagnostic markers for autoimmune diseases and probes for cell biology. Adv Immunol. 1989;44:93–151. doi: 10.1016/s0065-2776(08)60641-0. [DOI] [PubMed] [Google Scholar]
- Wolin S. L., Steitz J. A. The Ro small cytoplasmic ribonucleoproteins: identification of the antigenic protein and its binding site on the Ro RNAs. Proc Natl Acad Sci U S A. 1984 Apr;81(7):1996–2000. doi: 10.1073/pnas.81.7.1996. [DOI] [PMC free article] [PubMed] [Google Scholar]