Centromere protein C is a target of autoantibodies in Sjögren's syndrome and is uniformly associated with antibodies to Ro and La.

Objective: To determine which centromere proteins are recognized in Sjögren's syndrome (SS) and whether antibodies recognizing centromere proteins (CENP) B and CENP C identify a specific serologic subset.
Methods: Sera from 47 patients with SS, 12 xerostomic controls without SS, and 12 healthy controls were studied. All 47 patients met San Diego criteria for SS. Of these, 45 patients had primary SS and 2 had secondary SS with CREST. Sera were analyzed by immunoprecipitation of [35S] methionine-labeled Ro 52, La, and CENP B and C generated by coupled in vitro transcription/translation. Human salivary gland cells were also lysed and immunoprecipitated to determine antibody status against Ro 60. Serological and clinical profiles of patients recognizing CENP were defined. Proportions of sera recognizing CENP B, CENP C, Ro, or La across the 3 groups were compared using Fisher's exact test.
Results: Twenty-eight of 45 primary SS patients (62%) recognized Ro 52, and 24 patients (53%) recognized La. Ten of these 45 (22%) sera recognized CENP B or C. Furthermore, 7 of these 10 recognized exclusively CENP C; these 7 (100%) all tested positive for antibodies to both Ro 52 and La. This was in contrast to the group of SS patients that did not recognize CENP C alone, in whom anti-Ro 52 antibodies were found in 21 of 38 (55%; p = 0.034), and antibodies to La in 17 (45%; p = 0.01). Five of 7 CENP C positive sera were also positive for Ro 60. One of 3 patients with antibodies to CENP B also had antibodies to Ro 52, while none of these 3 had antibodies to La. Only patients with antibodies to CENP B showed a centromere pattern on immunofluorescence staining.
Conclusion: Antibodies to both CENP B and CENP C occur in SS. In a subset representing 15% of SS patients studied, these anticentromere antibodies recognize exclusively CENP C, and were uniformly associated with antibodies to Ro 52 and La.