Nuclear localization of immunoglobulins in renal biopsies of patients with lupus nephritis.

Immunofluorescent evaluation of renal biopsies from 19 patients with lupus nephritis revealed nuclear localization of immunoglobulins (IgG and IgM) in 6 patients. Homogeneous, nuclear rim and speckled patterns of nuclear localization were observed. The extent of localization varied, with only occasional nuclei fluorescing in 1 case, whereas approximately 50% of the nuclei exhibited fluorescence in the most extreme case. The phenomenon of nuclear localization of immunoglobulins was not observed in immunofluorescent studies of 225 renal biopsies from patients with conditions other than lupus nephritis. The possibility that nuclear localization of immunoglobulins occurred artifactually in the 6 patients was considered and was discounted by determining antinuclear antibody titers on serum obtained concurrently with the renal biopsy Nuclear localization was not confined to areas of histologically evident parenchymal destruction, indicating that antinuclear antibodies do not react only with nuclear antigens after tissue breakdown, but may gain access to intracellular antigens prior to cell dissolution.