image: This image shows two human neutrophils. The circular object about to be engulfed by the upper neutrophil is a Cryptococcus neoformans cell. view more
Credit: Albert Einstein College of Medicine
June 15, 2009 — (BRONX, NY) — In a study published in The Journal of Infectious Diseases, researchers from Albert Einstein College of Medicine of Yeshiva University have identified cells in blood that predict which HIV-positive individuals are most likely to develop deadly fungal meningitis, a major cause of HIV-related death. This form of meningitis affects more than 900,000 HIV-infected people globally—most of them in sub-Saharan Africa and other areas of the world where antiretroviral therapy for HIV is not available.
A major cause of fungal meningitis is Cryptococcus neoformans, a yeast-like fungus commonly found in soil and in bird droppings. Virtually everyone has been infected with Cryptococcus neoformans, but a healthy immune system keeps the infection from ever causing disease.
The risk of developing fungal meningitis from Cryptococcus neoformans rises dramatically when people have weakened immunity, due to HIV infection or other reasons including the use of immunosuppressive drugs after organ transplantation, or for treating autoimmune diseases or cancer. Knowing which patients are most likely to develop fungal meningitis would allow costly drugs for preventing fungal disease to be targeted to those most in need. (In the U.S., the widespread use of antiretroviral therapy by HIV-infected people, and their preventive use of anti-fungal drugs, has dramatically reduced their rate of fungal meningitis from Cryptococcus neoformans to about 2%.)
In this study, Liise-anne Pirofski, M.D., describes a technique for predicting which HIV-infected patients are at greatest risk for developing fungal meningitis caused by Cryptococcus neoformans. Dr. Pirofski is chief in the division of infectious diseases at Einstein.
Dr. Pirofski and her colleagues counted the number of immune cells known as IgM memory B cells in the bloodstream of three groups of individuals: people infected with HIV who had a history of fungal meningitis caused by Cryptococcus neoformans; people infected with HIV but with no history of the disease; and those with no history of either HIV infection or the disease.
"We were astounded to find a profound difference in the level of these IgM memory B cells between the HIV-infected groups," said Dr. Pirofski. "The HIV-infected people with fungal meningitis caused by Cryptococcus neoformans had much lower levels of these cells."
The research team wanted to know if the lower levels of IgM memory B cells in certain HIV-infected individuals resulted from the fungal disease, or whether their reduced levels of these cells preceded their development of the disease.
To find out, Dr. Pirofski analyzed frozen blood samples taken from HIV-infected patients before they had developed fungal meningitis due to Cryptococcus neoformans. Years before these HIV-infected patients were diagnosed with meningitis, their blood had far fewer IgM memory B cells than HIV-infected patients who didn't come down with the disease. This suggests that some people are predisposed to develop fungal meningitis because they have low levels of IgM memory B cells that may be due to their genetic makeup.
These findings could be important for many other immunocompromised patients in addition to those infected with HIV. "We think that knowing whether transplant recipients or other patients taking immunosuppressive drugs have low numbers of IgM memory B cells could be useful in deciding which patients should receive antifungal drugs to prevent meningitis caused by Cryptococcus neoformans," says Dr. Pirofski.
Krishanthi Subramanian, Ph.D., who did her thesis work in Dr. Pirofski's laboratory, is the first author of the study.
The paper, "IgM+ Memory B Cell Expression Predicts HIV-associated Cryptococcus neoformans Disease Status," appears in the June 15, 2009 online issue of The Journal of Infectious Diseases.
About Albert Einstein College of Medicine of Yeshiva University
Albert Einstein College of Medicine of Yeshiva University is one of the nation's premier centers for research, medical education and clinical investigation. It is the home to some 2,000 faculty members, 750 M.D. students, 350 Ph.D. students (including 125 in combined M.D./Ph.D. programs) and 380 postdoctoral investigators. Last year, Einstein received more than $130 million in support from the NIH. This includes the funding of major research centers at Einstein in diabetes, cancer, liver disease, and AIDS. Other areas where the College of Medicine is concentrating its efforts include developmental brain research, neuroscience, cardiac disease, and initiatives to reduce and eliminate ethnic and racial health disparities. Through its extensive affiliation network involving five hospital centers in the Bronx, Manhattan and Long Island – which includes Montefiore Medical Center, The University Hospital and Academic Medical Center for Einstein – the College runs one of the largest post-graduate medical training program in the United States, offering approximately 150 residency programs to more than 2,500 physicians in training. For more information, please visit www.aecom.yu.edu.
Journal
The Journal of Infectious Diseases