Staining of phagocytized Cryptococcus neoformans with DAPI.

The DAPI (4',6-diamidino-2-phenylindole)-fluorochrome was used to demonstrate phagocytized Cryptococcus neoformans using the mouse peritoneal cavity technique. These yeast cells were chosen because they are large and their capsules exhibit a deep yellow fluorescence which contrasts very well with the blue fluorescent nuclei of the phagocytes (preferentially macrophages). In other words, DAPI stains both, acid mucopolysaccharides and nuclear DNA. The capacity of the phagocyte nuclei to surround or even enclose the yeast cells was the most remarkable result. Generally, the application of DAPI in these phagocytosis experiments provides valuable information rapidly, easily and specifically.