Quality, Not Quantity, Important in Immune Control of HIV

A recent study found there was no significant difference in the number of HIV-fighting CD8+ cells between nonprogressors, people who have controlled HIV for up to 20 years without antiretroviral therapy, and others (progressors). The report appeared October 7, 2002, in the advanced online issue of Nature Immunology.

Previously, it had been thought that people who could not control HIV had too few CD8+ T cells. The current study showed, however, that both nonprogressors and others have about the same number of CD8+ T cells, but the cells of nonprogressors function better. Furthermore, CD8+ T cells from nonprogessors produce higher levels of perforin. Perforin (cytolysin) is believed to be one of the major effector molecules used by cytotoxic T cells to mediate targeted cell lysis.

The investigators' from the National Institute of Allergy and Infectious Diseases (NIAID, Bethesda, MD, USA; www.nih.gov), examined the immune systems of 40 people infected with HIV, including a group of about 15 nonprogressors. "Some of the newer techniques used in this study enabled us to see the functional differences in the CD8+ T cells of the two groups,” explained lead author Dr. Stephen Migueles. "The CD8+ T cells of people in the study who did not control HIV had retained only a limited ability to divide and produce perforin.”

"Understanding the mechanisms by which the immune systems of long-term nonprogressors control HIV is important to our development of effective vaccines,” said Dr. Anthony S. Fauci, director of the 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.”




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National Inst of Allergy and Infectious Diseases