Abstract

The aim of this study is to briefly review proliferation markers that can be applied in immunohistochemistry, with special emphasis on the monoclonal antibody Ki-67. This antibody reacts with a nuclear antigen present in all proliferating cells which are in the active parts of the cell cycle, i.e. G1, S, G2, and mitosis, but which is absent in G0 cells. Thus, with the help of this antibody a determination of the growth fraction of a given human cell population is possible. The use of this method in human tumor diagnostics is illustrated by three examples: malignant melanoma, breast carcinoma, and malignant Non-Hodgkin lymphoma. The results show that evaluation of the growth fractions by Ki-67 is not only a diagnostic importance, but also has independent prognostic value. In addition, preliminary data on the immunobiochemical characterization of native and recombinant Ki-67 antigen are presented. In immunoblot analysis, Ki-67 detects a doublet with apparent molecular weights of greater than 300 kDa. Furthermore, our data show that cDNA clones isolated from Lambda gT11 cDNA libraries encode for parts of the Ki-67 antigen and must contain the sequence that encodes for the epitope recognized by the Ki-67 antibody.