Scleroderma-specific autoantibodies: Should they be included in the diagnostic work-up for Sjögren's syndrome?

Objectives: Sicca complaints are a frequent reason for rheumatologic consultation. Testing for specific antibodies against Ro/SSA and La/SSB antigens and minor salivary gland (MSG) biopsy are among the main tools implemented in the diagnostic work-up. Anticentromere antibodies and sicca manifestations are frequently detected in Sjögren's syndrome (SS) and systemic sclerosis (SSc), respectively. Herein, we aimed to determine the frequency and clinical associations of a wide spectrum of scleroderma (SSc)-specific autoantibodies in consecutive patients referred for evaluation of possible SS.

Methods: Demographic, clinico-pathological, and laboratory data were recorded in 216 consecutive patients with sicca complaints. All study participants were tested for SSc-specific autoantibodies (against CENP, PM/Scl, Scl-70, Ku, NOR90, RP11, RP155, fibrillarin, PDGFR, and Th/To) using a commercially available immunoblot kit. According to band intensity, the identified autoantibodies were further classified in those with strong and medium titers.

Results: SSc-specific autoantibodies were detected in 41.7% (90/216) patients evaluated (19% at strong, 22.7% at medium titers) without significant differences between anti-Ro/SSA positive and negative groups. At strong titers was significantly higher in patients with MSG biopsies fulfilling SS histopathological criteria (30% vs 12.5%, p = 0.009). This association remained significant after adjustment for antibodies against Ro/SSA and La/SSB autoantigens [OR 95% (CI): 4.1 (1.5-10.6)].

Conclusion: SSc-specific autoantibodies are frequently detected among patients presenting with sicca complaints and at strong but not medium titers are independently associated with MSG biopsy positivity. Taken together, these data imply a useful role of SSc antibody testing in the diagnostic work-up and possibly in the classification criteria for SS.