Abstract
The objective of this study was to identify new autoantibodies that could be useful for the diagnosis of rheumatoid arthritis (RA) using immunoblotting on synovial membrane proteins which represent the best source of candidate RA autoantigens. A new target protein with a molecular weight of 26 kDa was found to be recognized by autoantibodies in RA sera and was identified using MALDI-TOF mass spectrometry and second-dimension electrophoresis as carbonic anhydrase III (CAIII). Three similar protein spots at 26 kDa were recognized by both human sera and monoclonal antibody (mAb) directed against CAIII on immunoblotting using the human recombinant CAIII. Interestingly, CAIII expression within the synovial membrane was not observed in non-RA patients and was differentially expressed among RA patients. The sensitivity of these new autoantibodies for RA, using an immunoenzymatic technique, was 17%. Specificity was high when comparing non-autoimmune diseases (100%), while it was found to be weak (67%) when comparing some other autoimmune diseases, and particularly systemic lupus erythematosus (SLE). In conclusion, this study demonstrates that these new autoantibodies against CAIII are not restricted to RA. However the expression of CAIII in the synovial membrane of RA warrants further investigation of the pathophysiological relevance of this finding.
Abbreviations | ||
CA | = | Carbonic anhydrase |
ELISA | = | Enzymatic Linked Immunosorbent Assay |
mAb | = | monoclonal antibody |
OD | = | Optical Density |
pAb | = | polyclonal antibody |
RA | = | Rheumatoid Arthritis |
SLE | = | Systemic Lupus Erythematosus |
Abbreviations | ||
CA | = | Carbonic anhydrase |
ELISA | = | Enzymatic Linked Immunosorbent Assay |
mAb | = | monoclonal antibody |
OD | = | Optical Density |
pAb | = | polyclonal antibody |
RA | = | Rheumatoid Arthritis |
SLE | = | Systemic Lupus Erythematosus |
Acknowledgements
We would like to thank the clinicians in the Departments of Rheumatology, Endocrinology and Internal Medicine for their diagnoses of patients with autoimmune or non-autoimmune diseases (CHLS, HCL), Mrs Paola Damaso for her secretarial assistance and Mrs V. Hawken for the complete revision of the English grammar. This study received support from the Hospices Civils de Lyon.