Cheyenne Daugherty, Benjamin Nelson, and Karen L. Wozniak Department of Microbiology and Molecular Genetics, Oklahoma State University, Stillwater, OK

Cryptococcus neoformans is an opportunistic fungal pathogen that is inhaled from the environment and causes over 225,000 yearly cases of cryptococcal meningitis in immune compromised patients, leading to 180,000 annual deaths in HIV/AIDS patients. Innate airway phagocytes, such as macrophages and dendritic cells (DCs), are the first cells to interact with the pathogen in the lungs. We hypothesized that specific subsets of innate airway phagocytes kill C. neoformans, while other subsets allow the pathogen to survive and grow intracellularly. We first examined the association between innate phagocytes and Cryptococcus using flow cytometry. Cells were also examined by fluorescence microscopy to examine the cryptococcal morphology within the cell. Results of flow cytometry studies showed C. neoformans interacts with all subsets of airway phagocytes. Microscopy showed that alveolar macrophages contained c-shaped organisms (indicating cell death) and langerin+ DCs contained replicating C. neoformans. These results indicate that C. neoformans does rely on certain specific airway phagocytes for intracellular survival, while other subsets can kill the organism. In order to verify that c-shaped organisms are dead, we conducted experiments with C. neoformans and the live/dead dye Fun-1. Fun-1 is used to determine metabolic activity of fungal organisms. We examined Fun-1 staining in live and heat-killed C. neoformans by flow cytometry. Results showed that we are able to distinguish between live and dead cells. Future studies will examine Fun-1 staining of C. neoformans following interaction with human airway phagocytes to verify killing or replication within each subset.  

Additional Abstract Information

Presenter: Cheyenne Daugherty

Institution: Oklahoma State University

Type: Poster

Subject: Microbiology

Status: Approved

Time and Location

Session: Poster 8
Date/Time: Tue 5:00pm-6:00pm
Session Number: 5637