The Sjögren's syndrome (SS) is an autoimmune rheumatic disease that targets salivary and lacrimal glands, characterized by a high concentration of autoantibodies in the serum. The anti-Ro and anti-La autoantibodies are present in approximately 70-90% of the patients with primary SS and this presence is correlated to extraglandular manifestations. The objective of this work was to explore the cellular apoptotic pathway triggered by binding and penetration of anti-Ro and anti-La autoantibodies, isolated from the total IgG fraction of patients with primary SS, in the human salivary gland cell line A-253.
The sera were obtained from 13 healthy volunteers and 13 patients with primary SS. The IgG was obtained from sera through precipitation with ammonium sulfate and the anti-La and anti-Ro autoantibodies were purified using Sepharose 4B-Ro and Sepharose 4B-La affinity columns. The methods used to evaluate the apoptosis were: DNA fragmentation, immunofluorescence and immunoenzymatic tests.
In the salivary gland cells, the anti-Ro and anti-La autoantibodies: 1) are able to penetrate; 2) induce DNA fragmentation and cleavage and activation of the effector caspase-3. In the same experimental condition, IgG purified from healthy sera did not have any apoptotic effect on the human salivary gland cell line.
Anti-Ro and anti-La autoantibodies mediate the apoptosis the human salivary gland cells A-253 in a caspase-3 dependent manner.