Objective: Anti-centromere antibody (ACA) is known to be specific for CREST syndrome, but individual studies showed variations in its distribution among related diseases. According to the authors′study on 56 ACA positive patients, 37 patients were known to have rheumatoid arthritis (RA). As a consequence, the authors studied the clinical significance of ACA positive RA patients. Methods: Specific clinical findings, radiologic studies, and laboratory data were investigated on 72 ACA positive and on 50 ACA negative RA patients. ACA tests were performed by indirect immunoflourescence assay with IT-1 cell line using IT-AIT kit (ImmunoThink^Ⱂ, Korea) Results: No specific differences were noted between the ACA positive and the negative group of RA. However, there were a few notable findings between the low titer and the high titer group of ACA positive RA. In comparison with the low titer group, the high titer group showed lesser disease activity, more cases of seronegative RA (39.2%＞4.8%), fewer radiologic evidences (45.1%＜71.4%), more cases accompanied with Raynaud's phenomenon (15.7%＞4.8%) and thyroid diseases (11.8%＞0%). They generally showed atypical RA patterns and the antibodies tend to remain at high titer state. Conclusion: Since the high titer ACA group of RA patients showed specific clinical findings, it is thought to be necessary to classify such group into a new subset of RA. And such classification would be helpful in diagnosing some atypical forms of RA patients. More studies on these new types of patients as well as their prognoses should be investigated in the future.

Keywords: Anti-centromere antibody, Rheumatoid arthritis