[Intranuclear structures of monkey kidney cells recognised by immunofluorescence and immuno-electron microscopy using...

Autoantibodies which react with a ribonucleoprotein material present in the saline extract of nuclei have been found in the sera of patients with Sharp's syndrome and in some cases of systemic lupus erythematosus and of systemic sclerosis. Such antibodies give a granular or reticulated immunofluorescence staining of the nuclei of mouse peripheral blood leukocytes. When cultures of monkey kidney cells (Macacus cynomolgus) were examined by immunofluorescence using such antibodies, it was found that the staining pattern depended on the state of the cell cultures. Nuclei of cells in stationary cultures showed the presence of perinucleolar granules of RNP whereas, within a few hours after subculture, the nuclei contained widely dispersed specks of antigen. In mitotic cells the antigen appears to be evenly dispersed throughout the cell volume with the exception of the chromosomes. Immuno-electron microscopy of cells treated 24 hours after subculture indicates that the specks correspond to aggregates of 200--250 A granules, probably interchromatin granules.