A number of octapeptides were generated from the sequences encoding the 60 kDa Ro/SSA peptide, the La/SSB autoantigen, the 70 kD nuclear ribonucleoprotein (nRNP), and the Sm B/B′ polypeptide, which represent linear epitopes for autoantibodies present in the sera of SLE and SS patients. These peptides are useful in solid phase assays for patients characterized by the presence of these autoantibodies, and can be used to categorize patients as to the likelihood of developing certain conditions associated with SLE. The peptides are also potentially useful in treatment of these patients using immobilized peptide to remove autoantibody and to block binding of the autoantibodies with patient molecules reactive with the autoantibodies.