Ki-67 Expression in Human Tumors Measured by Flow Cytometry

摘要

This study sought to combine FCM analysis of DNA with a proliferation-associatedantigen widely used in immunocytology, Ki-67. This antigen is expressed in the nucleus of proliferating cells throughout the cell cycle, but not in nonproliferating cells. Existing methods for simultaneous staining of DNA and Ki-67 are unreliable. Therefore, our efforts were directed to developing a satisfactory staining technique. A short fixation with 0.5% paraformaldehyde followed by exposure of cells to 0.1% Triton X-100 was found to be effective. Ki-67 expression in human tumors measured by FCM was then compared with immunocytologic measurements and to the S-phase fraction calculated by DNA analysis only. A significant correlation was found between Ki-67 expression determined by immunocytology and FCM in non-Hodgkin's lymphoma (NHL) (r=0.91). Significant correlation was also found between Ki-67 expression determined by FCM and DNA S-phase in these tumors (r=0.95). An interesting finding was the detection of low levels of Ki-67 in nonproliferating cells using FCM. This low level expression is not detectable by immunocytology, a technique less sensitive than FCM. (TTL)