an antibody showing an affinity for cell nuclei, demonstrated by exposing a cell substrate to the serum to be tested, followed by exposure to an antihuman-globulin serum conjugated with fluorescein; development of specific nuclear fluorescence is a positive reaction; this antibody is found in the serum of a high proportion of patients with systemic lupus erythematosus, rheumatoid arthritis, and certain collagen diseases, in some of their healthy relatives, and in about 1% of normal individuals.