Ro/SS-A and La/SS-B: autoantigens in Sjögren's syndrome?

Sjögren's syndrome is characterized serologically by the presence of autoantibodies against Ro/SS-A and La/SS-B. The mechanisms by which these autoantibodies arise is not clear at this moment. B cells capable of producing antibodies to Ro/SS-A and La/SS-B seem to be present in every individual; whether or not an individual indeed makes these antibodies is governed by T cells. Recent experiments from us and from others indicate that T cell tolerance towards Ro/SS-A and La/SS-B can be broken by immunization of normal mice with recombinant human Ro/SS-A or La/SS-B. The specificity of the T cells directing the anti-Ro/SS-A and anti-La/SS-B autoantibody response in these animals has not yet been elucidated. T cells may either be directed against foreign epitopes present on the human immunogen or they may be truly autoreactive. In patients with Sjögren's syndrome, a comparable immunization route might encompass product of viral origin directing the T cell response via RNA/protein complexes. Putative candidates comprise viruses that make use of RNAse polymerase-III, such as Epstein Barr virus, adenovirus, vesicular stomatitis virus en rabies virus.