NIH Researchers Find Possible Cause of Immune Deficiency Cases in Asia
Autoantibody May Cause Susceptibility to Opportunistic Infections
Aug. 22, 2012
A clinical study led by National Institutes of Health investigators has identified an antibody that compromises the immune systems of
HIV-negative people, making them susceptible to infections with opportunistic microbes such as nontuberculous mycobacteria (NTM).
In this study conducted at hospitals in Thailand and Taiwan, the researchers found that the majority of study participants with
opportunistic infections made an antibody against interferon-gamma (IFN-gamma), a cell-signaling molecule thought to play a
major role in clearing harmful infections. The study findings will appear online in the August 23rd issue of the New
England Journal of Medicine.
NTM are close relatives of the bacterium that causes tuberculosis and can cause severe lung disease. NTM and other
opportunistic infections are common in people with immune deficiency diseases, such as AIDS, but they are rare in people with
healthy immune systems. However, researchers in Southeast Asia have recently reported several cases of NTM infections in
people with no known problems with their immune systems.
The study, led by Sarah Browne, M.D., of the National Institute of Allergy and Infectious Diseases, and
Peter Burbelo, Ph.D., of the National Institute of Dental and Craniofacial Research, enrolled 203 people, ages 18 to 78 years old. Of these
participants, 52 had NTM infections, 45 had other opportunistic infections with or without NTM co-infection, 58 had tuberculosis, and
48 were healthy volunteers. All participants were HIV-negative.
The investigators examined participant blood samples for antibodies to cell-signaling molecules such as IFN-gamma.
Eighty-eight percent of the people with NTM or other opportunistic infections had antibodies that blocked their own IFN-gamma
The autoantibodies inhibited IFN-gamma function, hindering the immune system's ability to clear infection, causing
a syndrome that made these study participants more vulnerable to opportunistic infections. More work is needed to determine why
people in Southeast Asia appear to be predisposed to the development of this autoimmune condition. Because the average age of
the study participants with NTM or other opportunistic infections was 50 years, the investigators speculate that these
antibodies develop over time as a result of combined genetic and environmental factors. Having identified the likely
cause of this syndrome, the study authors say it may be possible to treat the underlying problem by targeting the
cells that make the IFN-gamma autoantibodies.
SK Browne et al. Adult onset immunodeficiency in Thailand and Taiwan. New England Journal of Medicine . DOI: 10.1056/NEJMoa1111160 (2012).
Sarah Browne, M.D., assistant clinical investigator, Laboratory of Clinical Infectious Diseases, NIAID, and Peter Burbelo, Ph.D., staff
scientist, Neurobiology and Pain Therapeutics, NIDCR, are available for comment.
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NIAID conducts and supports research-at NIH, throughout the United States, and worldwide-to study the causes of infectious and immune-mediated diseases, and to develop better means of preventing, diagnosing and treating these illnesses. News releases, fact sheets and other NIAID-related materials are available on the NIAID Web site at www.niaid.nih.gov.
About the National Institutes of Health (NIH):
NIH, the nation's medical research agency, includes 27 Institutes and Centers and is a component of the U.S. Department of Health and Human Services. NIH is the primary federal agency conducting and supporting basic, clinical, and translational medical research, and is investigating the causes, treatments, and cures for both common and rare diseases. For more information about NIH and its programs, visit www.nih.gov .
Source: NIH News
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