Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

T cell lifespan during HIV infection

16.09.2003


Scientists have long held the prevailing view that during HIV infection the depletion of T cells is the result of direct HIV virus–mediated killing. In the September 15 issue of the Journal of Clinical Investigation, Marc Hellerstein and colleagues at the University of California in Berkeley report that it is the chronic activation of the host immune system in response to HIV infection that primarily contributes to T cell loss.



A series of influential studies published in the mid-1990s described the rapid decay of viral load following administration of highly active antiretroviral therapy (HAART), and proposed that HIV infection was associated with a high rate of virus turnover and short lifespan of infected cells. This suggested that HIV infection of susceptible CD4+ T cells led to such high rates of cell death, that compensatory T cell proliferation was inadequate to maintain sufficient T cell numbers and therefore compromised the ability of the immune system to fight the virus.

This view was recently challenged by observations that not only were virus-infected cells dying, but a greater number of uninfected bystander T cells underwent programmed cell death that was not a direct result of HIV infection. Therefore, a new theory has been proposed in which high levels of T cell proliferation reflects a state of chronic immune activation following HIV infection as opposed to simple compensatory proliferation.


Hellerstein and colleagues used a highly innovative technique for measuring the dynamics of T cell turnover in 3 groups of individuals: (i) HIV-infected; (ii) HIV-infected HAART-treated; and (iii) uninfected. They authors found that most of the increased T cell turnover during HIV infection involved a subset of memory T cells – those cells which have encountered prior infection and can rapidly mobilize and clone themselves should the same foreign antigen be encountered during a subsequent infection. The authors concluded that the increased degree of proliferation of this T cell subset was the result of chronic immune activation and not the result of a mechanism striving to compensate for the loss of T cells directly killed by the virus. The increased degree of memory T cell turnover results in a lack of long-lived memory T cells available to assist newly infected cells. The authors did however demonstrate that HAART was able to ameliorate the defect in the production of these long-lived cells.

This identification of this fast-replicating but short-lived subset of T cells aids our understanding of how the body reacts to HIV infection and how HIV wields its destructive power. In an accompanying commentary Guido Silvestri and Mark Feinberg from the Emory Vaccine Center in Atlanta, Georgia, discuss how the dynamics of the T cell population effects the progression of HIV disease. These authors add that the present study "provides important clues as to how HIV infection leads to CD4+ T cell depletion and AIDS". It is still not clear how HIV induces this chronic state of immune activation and why this is so disruptive to the proper overall functioning of the host immune system. Silvestri and Feinberg continue, "some of these questions can be resolved with future application of the innovative and informative labeling techniques pioneered by Hellerstein and colleagues".


###
TITLE: Subpopulations of long-lived and short-lived T cells in advanced HIV-1 infection

AUTHOR CONTACT:
Marc Hellerstein
University of California, Berkeley, California, USA.
Phone: (510) 642-0646
Fax: (510) 642-0535
E-mail: march@nature.berkeley.edu

ACCOMPANYING COMMENTARY:
Turnover of lymphocytes and conceptual paradigms in HIV infection

AUTHOR CONTACT:
Mark B. Feinberg
Emory Vaccine Center, Atlanta, Georgia, USA.
Phone: (404) 727-4374
Fax: (404) 727-8199
E-mail: mbf@sph.emory.edu

Brooke Grindlinger | EurekAlert!
Further information:
http://www.the-jci.org/press/19799.pdf
http://www.the-jci.org/press/17533.pdf
http://www.jci.org/

More articles from Health and Medicine:

nachricht Cholesterol-lowering drugs may fight infectious disease
22.08.2017 | Duke University

nachricht Once invincible superbug squashed by 'superteam' of antibiotics
22.08.2017 | University at Buffalo

All articles from Health and Medicine >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Fizzy soda water could be key to clean manufacture of flat wonder material: Graphene

Whether you call it effervescent, fizzy, or sparkling, carbonated water is making a comeback as a beverage. Aside from quenching thirst, researchers at the University of Illinois at Urbana-Champaign have discovered a new use for these "bubbly" concoctions that will have major impact on the manufacturer of the world's thinnest, flattest, and one most useful materials -- graphene.

As graphene's popularity grows as an advanced "wonder" material, the speed and quality at which it can be manufactured will be paramount. With that in mind,...

Im Focus: Exotic quantum states made from light: Physicists create optical “wells” for a super-photon

Physicists at the University of Bonn have managed to create optical hollows and more complex patterns into which the light of a Bose-Einstein condensate flows. The creation of such highly low-loss structures for light is a prerequisite for complex light circuits, such as for quantum information processing for a new generation of computers. The researchers are now presenting their results in the journal Nature Photonics.

Light particles (photons) occur as tiny, indivisible portions. Many thousands of these light portions can be merged to form a single super-photon if they are...

Im Focus: Circular RNA linked to brain function

For the first time, scientists have shown that circular RNA is linked to brain function. When a RNA molecule called Cdr1as was deleted from the genome of mice, the animals had problems filtering out unnecessary information – like patients suffering from neuropsychiatric disorders.

While hundreds of circular RNAs (circRNAs) are abundant in mammalian brains, one big question has remained unanswered: What are they actually good for? In the...

Im Focus: RAVAN CubeSat measures Earth's outgoing energy

An experimental small satellite has successfully collected and delivered data on a key measurement for predicting changes in Earth's climate.

The Radiometer Assessment using Vertically Aligned Nanotubes (RAVAN) CubeSat was launched into low-Earth orbit on Nov. 11, 2016, in order to test new...

Im Focus: Scientists shine new light on the “other high temperature superconductor”

A study led by scientists of the Max Planck Institute for the Structure and Dynamics of Matter (MPSD) at the Center for Free-Electron Laser Science in Hamburg presents evidence of the coexistence of superconductivity and “charge-density-waves” in compounds of the poorly-studied family of bismuthates. This observation opens up new perspectives for a deeper understanding of the phenomenon of high-temperature superconductivity, a topic which is at the core of condensed matter research since more than 30 years. The paper by Nicoletti et al has been published in the PNAS.

Since the beginning of the 20th century, superconductivity had been observed in some metals at temperatures only a few degrees above the absolute zero (minus...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Call for Papers – ICNFT 2018, 5th International Conference on New Forming Technology

16.08.2017 | Event News

Sustainability is the business model of tomorrow

04.08.2017 | Event News

Clash of Realities 2017: Registration now open. International Conference at TH Köln

26.07.2017 | Event News

 
Latest News

Cholesterol-lowering drugs may fight infectious disease

22.08.2017 | Health and Medicine

Meter-sized single-crystal graphene growth becomes possible

22.08.2017 | Materials Sciences

Repairing damaged hearts with self-healing heart cells

22.08.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>