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2002 NOV 20 - (NewsRx.com & NewsRx.net) -- Scientists are beginning to change their thinking about why the immune systems of most people infected with HIV cannot control the spread of the virus while the immune systems of a rare group of individuals, called long-term nonprogressors, can.
For some time, scientists thought that people who could not control HIV had too few HIV-fighting white blood cells called CD8+ T cells. However, a new study suggests the difference is not the number but the quality of these cells: both nonprogressors and others have about the same number of HIV-fighting CD8+ T cells, but the cells of nonprogressors function better.
"Understanding the mechanisms by which the immune systems of long-term nonprogressors control HIV is important to our development of effective vaccines," said Anthony S. Fauci, director of the National Institute of Allergy and Infectious Diseases (NIAID). "Studies like this one, which reveal basic knowledge about how the immune system interacts with HIV, form the foundation of our effort to fight this disease." Details of the study, conducted by NIAID scientists, appears in Nature Immunology (2002;3(11):1061-1068).
Instead of attacking HIV directly, CD8+ cells inhibit virus spread by killing off other immune system cells infected with HIV. "For some time we have known that even patients who cannot control HIV maintain high numbers of HIV-specific CD8+ T cells," said senior author Mark Connors, MD, of NIAID's Laboratory of Immunoregulation.
However, this study represents the first time scientists have observed a difference in the HIV-specific CD8+ T-cell response of nonprogressors, he said. This study also suggests a mechanism whereby the CD8+ T cells of nonprogressors control HIV and those of most individuals do not.
Connors and colleagues ...
Source: HighBeam Research, Study shows why some immune systems control HIV.