Immunoelectron-microscopic localization of a proliferation-associated antigen Ki-67 in MCF-7 cells

Histochem J. 1990 Sep;22(9):498-506. doi: 10.1007/BF01007235.


Immunocytochemistry using the monoclonal antibody Ki-67 is a commonly used method to assess proliferative activity of malignant tumours, Ki-67 reacts with proliferating cells with an antigen, whose structure, function and exact locations are unknown. We studied the subcellular location of Ki-67 in MCF-7 cells using immunoelectron microscopy. In the interphase cells, Ki-67 immunoreactivity was localized in the nucleolus, mainly in the nucleolar cortex. In particular, areas of the granular component of the nucleolus were strongly stained. Weak spot-like nucleoplasmic immunostaining was also seen outside the nucleolus. During prophase Ki-67 antigen was localized on the surfaces of the condensed chromatin and during metaphase on the surface of the chromosomes. After cell division and prior to formation of new nucleoli, Ki-67 immunoreactivity was located in the nucleoplasm. Quantification of Ki-67 immunofluorescence signal by flow cytometry revealed highest Ki-67 levels in mitotic cells. The location of Ki-67 is very similar to certain recently described proteins of nucleolar preribosomes suggesting that Ki-67 may also be a component of the preribosomes.

MeSH terms

  • Antibodies, Monoclonal
  • Antigens, Neoplasm / analysis*
  • Antigens, Surface / analysis*
  • Breast Neoplasms / immunology
  • Breast Neoplasms / ultrastructure
  • DNA, Neoplasm / chemistry
  • Female
  • Flow Cytometry
  • Fluorescent Antibody Technique
  • Humans
  • Immunohistochemistry
  • Ki-67 Antigen
  • Microscopy, Immunoelectron
  • Tumor Cells, Cultured / immunology
  • Tumor Cells, Cultured / ultrastructure*


  • Antibodies, Monoclonal
  • Antigens, Neoplasm
  • Antigens, Surface
  • DNA, Neoplasm
  • Ki-67 Antigen