Distinct recognition of antibodies to centromere proteins in primary Sjögren's syndrome compared with limited scleroderma

Background: Anticentromere antibodies are characteristically observed in scleroderma but have recently been reported in other autoimmune rheumatic disorders, including Sjögren's syndrome. It is not known whether distinct centromere proteins (CENP) are targeted in primary Sjögren's syndrome (pSS) and scleroderma. Objective: To determine whether antibodies to CENP-B and CENP-C are present in these two disorders. Methods: Sera from 45 patients with pSS and 33 with limited scleroderma were studied. All patients met classification criteria for pSS and scleroderma, respectively. Sera were used to immunoprecipitate in vitro translated CENP-B and CENP-C. The proportions recognising CENP-B or CENP-C were compared. Results: 10 of 45 patients (22%) with pSS and 18 of 33 (55%) with scleroderma had antibodies recognising CENPs (p = 0.004). Seven of 10 (70%) CENP positive patients with pSS recognised CENP-C alone, compared with one of 18 (6%) CENP positive patients with scleroderma (odds ratio (OR) = 40 (95% confidence interval (CI), 3.5 to 450) (p = 0.003). In contrast, the majority (15 of 18 (83%)) of CENP positive scleroderma sera recognised both CENP-B and CENP-C, compared with none of 10 pSS sera (OR = 93 (95% CI, 4.4 to 1979) (p = 0.0001). Conclusions: The pattern of CENP recognition differs markedly in pSS and limited scleroderma. While patients with pSS predominantly recognise CENP-C alone, dual recognition of CENP-B and CENP-C is most frequent in scleroderma. These findings suggest that obtaining antibodies to specific centromere antigens is useful diagnostically, and imply that distinct mechanisms underlie the unique patterns of centromere autoreactivity in pSS and scleroderma.