HIV targets white blood cells with surface receptors called CD4. These CD4, or helper, T-cells normally orchestrate the body's immune response. In response to a particular pathogen, they induce cytotoxic T-cells (or CD8 T-cells) and other immune cells to multiply and differentiate--that is, to become specially equipped to recognize and target a particular pathogen, or antigen. When the researchers analyzed T-cells from a group of untreated HIV infected individuals at different stages--acute infection, chronic infection without progression, and chronic infection with signs of progression--they found to their surprise that during acute HIV infection, the vast majority (80%90%) of the overall CD8 T-cell population was activated--not just the HIV-specific CD8 T-cells. CD8 T-cells specific to two other chronic (and usually benign) pathogens, EpsteinBarr virus and cytomegalovirus, showed significant activation levels during HIV acute infection. And as HIV/AIDS progresses, many of the CD8 T-cells developed to a state of senescence where they are no longer active.
These results show that chronic and nonspecific overactivation of the immune system during HIV infection produces a large pool of highly differentiated T-c
Contact: Barbara Cohen
Public Library of Science