What does KI67

The Ki67 antigen

The Ki67 antigen is a Proliferation markers, i.e. it stains the cells in the tissue that are multiplying, the so-called Growth fraction. During the cell cycle, this antigen is expressed in the G1, S, G2 and M phases. Resting cells, i.e. cells that are in the G0 phase, do not express the Ki67 antigen. The coloring for Ki67 therefore provides indirect information about the Speed ​​of growth of a tumor and is therefore of inestimable value in routine diagnostics. The representation of the Ki67 antigen can also provide valuable assistance in deciding between benign, preneoplastic and malignant changes.

There are several antibodies against Ki67. The antibody clone that gave this antigen its name (Ki stands for Kiel and refers to the Institute for Pathology at Kiel University Hospital) only worked reliably on cryostat sections and was only suitable for routine diagnostics to a limited extent. The clone MIB-1 was the first paraffin antibody with which the Ki67 antigen could also be shown in routine histology. By the way, the abbreviation for MIB - Schleswig-Holstein residents should also know this - stands for “made in Borstel”. We use the common paraffin clone KiS5 in diagnostics (that's right, it comes from the state capital!).

Reactive changes in the epithelium in Barrett's mucosa: The epithelium matures to the surface. No proliferative cells can be seen in the surface epithelium. The topology of the normal mucosa is preserved with regard to the kinetics of proliferation.

Dysplastic changes in Barrett's mucosa (high-grade neoplasia): The proliferative cell deposit extends into the surface epithelium. As a sign of cellular disorganization, there is no surface maturation.

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Dr. A. Turzynski
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