Detection of anti-SSA/Ro and SSB/La antibodies using the immunoblotting method and clinical analysis

Sera from 84 patients with connective tissue diseases and 30 healthy volunteers were examined for the presence of anti-SSA/Ro, SSB/La antibodies using immunoblotting techniques, and a comparative study of the results of the double immunodiffusion technique was performed. The SSA/Ro and SSB/La antigens were prepared from human spleen, rabbit thymus acetone powder, and the KB cell line, a human epithelial cell line. By immunoblotting, the SSA/Ro antibody was shown to react mainly with 58 KD peptide, while the SSB/La antibody reacted with 42 KD and 40 KD peptides. Some SSA/Ro positive antisera were also reactive with 64 KD peptide. Using the immunoblotting method, we have found that over 83% of SLE patients possess the SSA/Ro antibody, and 41% possess the SSB/La antibody. The relationship between the presence of these antibodies and SLE abnormalities was examined. No abnormality was seen with significant frequency among patients in the SSA/Ro positive group of SLE. The SLE patients with SSB/La antibody were characterized by a low prevalence of oral ulcers, a low titer for nDNA antibody, and presence of the rheumatoid factor and the anti-Sm antibody. In addition, the SLE patients with an autoantibody reactive with an additional 64 KD band exhibited a low prevalence of facial rash, the presence of anti-nDNA antibody, and a low CH50 value. We speculated on the possibility of a racial difference in this clinical heterogeneity as compared with previous data in Europe and the U.S.A.