Scientists Discover How HIV Deactivates Immune Cells

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Main Category: HIV / AIDS
Also Included In: Immune System / Vaccines;  Biology / Biochemistry;  Infectious Diseases / Bacteria / Viruses
Article Date: 21 Aug 2006 - 9:00 PDT


How HIV persistently weakens immune cells has been discovered by scientists at Massachusetts General Hospital, Boston, USA. This breakthrough could ultimately lead to finding ways of treating HIV more successfully.

You can read about this research in the journal Nature.

When HIV builds up in the blood CD8 cells - immune cells that target viruses - start to produce too much of a receptor molecule that eventually makes the CD8 weaker. They overproduce a receptor molecule, known as Programmed Death-1 (PD-1). As the immune cells become weaker, they produce fewer cytokines. Cytokines are chemicals that destroy viruses.

CD8 cells become inundated with PD-1 and eventually stop working. The higher the accumulation of HIV, the less the CD8 cells function.

Bruce Walker, head researcher, said "But it did not make sense that these cells were found in high numbers in persons with late stage AIDS, indicating they were somehow not doing their job. These new findings finally make sense out of our early discoveries and subsequent findings by others in the field. The immune cells are there, but they have been turned off in persons with high viral loads."

The trouble with blocking PD-1 is that there is a chance the patient might develop serious autoimmune disease. Rowland-Jones wrote a commentary which accompanies the study published in Nature. According to her, this is exactly what happened with mice bred not to have the gene. PD-1 is most likely vital in preventing the immune system attacking itself.

PD-1 expression on HIV-specific T cells is associated with T-cell exhaustion and disease progression
Cheryl L. Day, Daniel E. Kaufmann, Photini Kiepiela, Julia A. Brown, Eshia S. Moodley, Sharon Reddy, Elizabeth W. Mackey, Joseph D. Miller, Alasdair J. Leslie, Chantal DePierres, Zenele Mncube, Jaikumar Duraiswamy, Baogong Zhu, Quentin Eichbaum, Marcus Altfeld, E. John Wherry, Hoosen M. Coovadia, Philip J. R. Goulder, Paul Klenerman, Rafi Ahmed, Gordon J. Freeman and Bruce D. Walker
Naturedoi:10.1038/nature05115
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Written by: Christian Nordqvist
Editor: Medical News Today
Copyright: Medical News Today
Not to be reproduced without permission of Medical News Today

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