Enzyme immunoassay for the qualitative and quantitative determination of IgG antibodies against SS-B/La in human serum. La, the antigen of SS-B/La-autoantibodies, is a 50 kDa phosphoprotein, component of certain ribonucleoprotein (RNP) complexes and involved in RNA metabolism (as transcription termination factor for RNA polymerase III). SS-B/La-antibodies exhibit a high prevalence (40-90%) for the Sjögren-syndrome (SS), an inflammatory autoimmune disorder of the exocrine glands. They are also associated with systemic lupus erythematosus (SLE); especially with some of its variants (e.g. neonatal LE). In this respect, they resemble SS-A/Ro-antibodies. Often, both antibody species occur concomitantly. However, while SS-A/Ro-Ab can be found separately, SS-B/La-Ab almost exclusively occurs together with SS-A/Ro-Ab. Hence, SS-B/La-antibodies exhibit a somewhat lower sensitivity for SS and SLE, as compared to SS-A/Ro-antibodies, but a higher degree of specificity.