Anti-protein kinase NII antibodies in rheumatic autoimmune diseases

Antibodies against nuclear protein kinase NII were detected by radioimmunoassay in the sera of patients with systemic lupus erythematosus and mixed connective tissue disease but not in sera from normal individuals or from patients with rheumatoid arthritis. Immunoglobulins derived from sera containing the anti-kinase antibodies inhibited the activity of protein kinase NII in vitro but had no effect on the activity of cytoplasmic cyclic AMP-dependent protein kinase.