Differential expression of Ro/SSA 60 kDa and La/SSB, but not Ro/SSA 52 kDa, mRNA and protein in minor salivary glands from patients with primary Sjögren's syndrome.

OBJECTIVE: To analyze the protein and messenger RNA (mRNA) expression of La/SSB, Ro/SSA 60, and Ro/SSA 52 antigens in minor salivary glands (MSG) from patients with primary Sjögren's syndrome (pSS).

METHODS: La/SSB, Ro/SSA 60, and Ro/SSA 52 protein expression was studied by immunohistochemistry in MSG from 26 patients with pSS and 16 controls. mRNA expression was determined by real-time polymerase chain reaction in MSG of 10 patients with pSS and 7 controls.

RESULTS: La/SSB and Ro/SSA 60, but not Ro/SSA 52, mRNA expression was higher in samples from patients with pSS compared to controls (p < 0.05). La/SSB protein had higher expression in the cytoplasm of ductal cells than in the cytoplasm of mucous acinar cells in patients with pSS (p = 0.013) but not in controls. Ro/SSA 60 had higher expression in the cytoplasm of ductal cells than in the cytoplasm of serous acinar cells in patients with pSS (p = 0.006) but not in controls. The Ro/SSA 52 expression pattern was similar in patients and controls. There was no association between circulating autoantibodies to Ro/SSA or La/SSB and the aberrant expression of the cognate autoantigens.

CONCLUSION: The increased Ro/SSA 60 and La/SSB mRNA expression in MSG of patients with pSS as well as the differential Ro/SSA 60 and La/SSB protein expression in ductal cells of MSG in patients with pSS suggest that these these 2 autoantigens, but not Ro/SSA 52, are probably involved in triggering and maintaining the tissue-specific autoimmune response in pSS MSG and may contribute to the antigen-driven immune response and local autoantibody production in pSS.