Precipitating antibodies to cellular antigens in Sjögren's syndrome, rheumatoid arthritis, and other organ and nonorgan-specific autoimmune diseases.
The prevalence of three precipitating antibodies, anti-SS-A anti-SS-B, and rheumatoid arthritis precipitin (RAP), reacting with an extract of the human lymphoid cell line Wil2, was studied in the sicca syndrome, Sjögren's syndrome with rheumatoid arthritis, rheumatoid arthritis, various seronegative spondyloarthritides, and organ and nonorgan-specific autoimmune disease. Anti-SS-A and snti-SS-B occurred most frequently in the sera of patients with the sicca syndrome whereas RAP occurred most frequently in seropositive rheumatoid arthritis sera. However, the data did not support previous studies where patients with sicca syndrome had a high incidence of anti-SS-A and/or -SS-B antibodies but had a low frequency of RAP, and patients with Sjögren's syndrome in association with rheumatoid arthritis had a high incidence of RAP but a low incidence of anti-SS-A and/or -SS-B. Instead the three antibodies were present in both forms of Sjögren's syndrome. This suggested a difference in the diseases in the UK compared to the USA, or that these antibodies do not have the more subtle diagnostic specificity that was originally suggested.