Isotype distribution of anti-Ro/SS-A and anti-La/SS-B antibodies in plasma and saliva of patients with Sjögren's syndrome.

In this study an ELISA assay was used to quantify the levels of antibodies against the recombinant Ro 52 kD, Ro 60 kD, and La 48 kD proteins in plasma and saliva of 17 Sjögren's syndrome patients. The levels of total IgG, IgA, and IgM were also quantified. About one third of the patients had salivary enrichment of IgA and IgM against the Ro 52 kD, Ro 60 kD, and La 48 kD antigens and IgG against La 48 kD, while no enrichment of IgG against Ro 52 kD and Ro 60 kD was found. Most correlations between plasma and saliva levels of antigen specific antibodies were highly significant, as were most correlations between focus score and levels of antigen specific antibodies in plasma and saliva. In total, the results support the hypothesis that autoantibodies are produced in the salivary glands. The strong correlation between focus score and plasma and saliva levels of autoantibodies, indicates that the local autoantibody production is a consequence of local inflammation.