HIV-infected people who carry a gene for Fc gamma receptor FCGR3A 158V face a 20-fold greater risk of contracting cryptococcal disease, according to a study in mBio this week. Cryptococcal disease is a risk for everyone with HIV who has a very low level of CD4+ T cells, but those with the gene for FCGR3A 158V have an immune cell receptor that binds tightly to antibody-bound Cryptococcus neoformans. Perversely, this tight binding by a vigilant immune system may mean the patient's own immune system strength becomes a weakness when facing C. neoformans.
"We found that this high affinity Fc receptor polymorphism was very highly overrepresented in the patients that got cryptococcal disease," says corresponding author Liise-anne Pirofski of the Albert Einstein College of Medicine & Montefiore Medical Center in The Bronx, New York. Patients with two copies of the high affinity Fc receptor gene had an almost 20-fold increased risk of contracting the disease.
"It's surprising that a receptor involved with a higher capacity to bind immune complexes would be associated with susceptibility in patients with HIV," says Pirofski, since phagocytosis of immune complexes is always thought of as a mechanism for fighting invading microorganisms.
Click on the source link to read more on mBio's blog, mBiosphere...