In results from a MACS study published online August 27, 2013 by the American Society of Microbiology, some people living with HIV face a 20-times higher risk for the fungal disease Cryptococcal neoformans, or “crypto”. This is due to the presence of a gene that expresses a protein dubbed “Fc”.
Crypto is common in the environment, and most healthy individuals don’t encounter problems with it. However, people with weakened immune systems and people with HIV who have lower CD4 counts (<200) are at a higher risk for disease. In HIV-positive people, C. neoformans often results in the brain disease fungal meningitis.
Scientists enrolled 164 men: 55 were HIV-positive and had developed crypto, while 54 were HIV-positive and didn’t develop crypto and another 55 were HIV-negative. Comparing the three groups, they found a strong association between the Fc-related gene and the higher risk for crypto.
Through further study, scientists discovered that those immune cells which expressed Fc on their surface may more easily permit the fungus to bind to them. This could, in turn, allow the fungus to replicate more easily inside cells or to be passed to other parts of the immune system.
Further study that confirms this observation could serve to develop a simple blood test to predict who is more at risk. This could eventually help prevent unnecessary disease and save lives.
RESEARCH:
S Rohatgi, et al. Fc Gamma Receptor 3A Polymorphism and Risk for HIV-Associated Cryptococcal Disease. American Society for Microbiology. August 27, 2013.