ACRIDINE ORANGE 



Fluorescence Microscopy Method for C5rtodiagnosis of 

 Cancer and Differential Staining of Nucleic Acids 



Used as a fluorchrome at the appropriate pH, acridine orange 

 presents highly polychrome pictures. DNA of the nucleus, for 

 instance, is demonstrated in green or yellow fluorescence, while 

 RNA of the nucleolus and of the cytoplasm fluoresces in reddish 

 brown to orange with increasing concentrations to bright red. 

 Proliferating malignant cells are readily characterized by an RNA 

 content which greatly exceeds that of the non-malignant cells of 

 origin (Brachet, 1950; Chargaff & Davidson, 1955; Pirozynski & 

 L. Von BertalanflFy, 1955; L. Von Bertalanffy & F. D. Bertalanffy, 

 i960). These cytoplasmic changes are readily observable by the 

 acridine orange fluorescence method. 



The method, which was first developed for exfoliative cytology 

 in gynaecology and later applied to the diagnosis of malignancies 

 of the respiratory system, is based upon the metachromatic 

 properties of acridine orange, giving diflFerential staining of the 

 two types of nucleic acids of the cell (L. Von Bertalanffy & I. 

 Bickis, 1956). It is claimed that because of the striking differences 

 between normal and malignant cells shown by this method, 

 malignant cell elements can be recognized even by observers 

 with little cytological training. 



F. D. Bertalanffy (i960) states that cytodiagnosis is one of the 

 most readily available and effective means of cancer diagnosis. 

 All that is needed for the diagnosis of the presence or absence 

 of malignant lesions in certain parts of the body, is a small sample 

 of sputum, vaginal smears, or other material collected during 

 routine examination. 



The acridine orange method is widely used clinically in Canada 

 and in the United States of America, and the information given 

 here has been compiled almost entirely from reprints and personal 

 communications from the original author, Professor Felix D. 



D* 93 



