THE ASSOCIATION BETWEEN CELL-PROLIFERATION AND APOPTOSIS - STUDIES USING THE CELL CYCLE-ASSOCIATED PROTEINS KI67 AND DNA-POLYMERASE-ALPHA

The process of apoptosis is associated with the inappropriate expressi on of cell cycle regulatory proteins, which has led to the proposal th at the apoptotic pathway represents an abortive attempt to pass throug h the cell proliferation cycle, To investigate this hypothesis, we exa mined the expression of two proliferation-associated antigens in apopt otic cells. Apoptotic bodies seen in a range of normal and pathologica l tissues are often positive for the Ki67 antigen, indicating that the se cells mere in the cell cycle during the period that they died, In c ontrast, spontaneous apoptosis of human polymorphonuclear leukocytes m aintained in culture was not associated with the expression of either Ki67 or DNA polymerase a. In addition, apoptotic bodies in the pre-men strual endometrium did not express the Ki67 antigen, These results ind icate that, contrary to previous suggestions, apoptosis does not alway s depend on cell cycle entry, The use of antibodies to Ki67 should be valuable in defining the association of apoptosis with proliferation i n a wide range of cells and tissues.