Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

How HIV outmaneuvers the immune system

05.11.2002


T cells and antibody-producing B cells carry out immune defense against specific pathogens such as viruses. Antibodies and T cell receptors are highly diverse molecules that can recognize millions of different molecules. Upon encounter of a foreign antigen (such as a molecule from the surface of a virus), T cells and B cells whose receptors match that particular antigen expand dramatically, providing the immune system with a large number of very specific defenders. After an attack is fought off, the overall numbers of specific T and B cells go down again, but a few of them become long-lived so-called "memory cells" that ensure a quick re-mobilization should the same type of attacker strike again.



T cells consist of two major groups: CD4-positive T helper cells (who help other immune cells in mounting an effective response) and CD8-positive killer T cells. HIV infects and destroys CD4-positive cells, leaving patients with a crippled immune system. Throughout the course of HIV disease, however, patients have high levels of HIV-specific killer T cells. Early after initial infection, these cells are able to effectively kill the virus and reduce viral load. On the other hand, during the later stage of disease killer T cells, while still present, seem no longer able to control the virus. In an article in the November 4 issue of the Journal of Clinical Investigation, Premlata Shankar and colleagues from the Center for Blood Research at Harvard Medical School suggest why this might be the case.

The researchers compared killer T cells from HIV infected asymptomic individuals with those from symptomatic AIDS patients. They examined the killer cells’ ability to eliminate target cells infected with laboratory strains of HIV on one hand, and with autologous virus (isolated from the patient) on the other. What they found is that killer T cells from asymptomatic individuals can recognize and kill both types of target cells. In contrast, the killer T cells from symptomatic patients, while still able to recognize and eliminate the laboratory strain targets, no longer killed target cells that were infected with their own, autologous, virus. This is likely due to the virus’ propensity to mutate and the in inability of the patient’s weakened immune system to keep up with the changing virus.


These results demonstrate that the high number of HIV-specific killer T cells found in AIDS patients are remnants of what used to be an effective response early after infection but no longer recognize the mutated autologous virus. Moreover, these findings reveal that conventional assays to measure killer T cell responses in HIV patients--which focus on responses to laboratory strains--do not accurately reflect but overestimate the response to the patient’s autologous virus.


CONTACT:
Premlata Shankar
Harvard Medical School
The Center for Blood Research
800 Huntington Avenue
Boston, MA 02115
USA
PHONE: 617-278-3476
FAX: 617-278-3403
E-mail: shankar@cbr.med.harvard.edu

Brooke Grindlinger | EurekAlert!
Further information:
http://www.jci.org/

More articles from Health and Medicine:

nachricht Norovirus evades immune system by hiding out in rare gut cells
12.10.2017 | University of Pennsylvania School of Medicine

nachricht Flexible sensors can detect movement in GI tract
11.10.2017 | Massachusetts Institute of Technology

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: Neutron star merger directly observed for the first time

University of Maryland researchers contribute to historic detection of gravitational waves and light created by event

On August 17, 2017, at 12:41:04 UTC, scientists made the first direct observation of a merger between two neutron stars--the dense, collapsed cores that remain...

Im Focus: Breaking: the first light from two neutron stars merging

Seven new papers describe the first-ever detection of light from a gravitational wave source. The event, caused by two neutron stars colliding and merging together, was dubbed GW170817 because it sent ripples through space-time that reached Earth on 2017 August 17. Around the world, hundreds of excited astronomers mobilized quickly and were able to observe the event using numerous telescopes, providing a wealth of new data.

Previous detections of gravitational waves have all involved the merger of two black holes, a feat that won the 2017 Nobel Prize in Physics earlier this month....

Im Focus: Smart sensors for efficient processes

Material defects in end products can quickly result in failures in many areas of industry, and have a massive impact on the safe use of their products. This is why, in the field of quality assurance, intelligent, nondestructive sensor systems play a key role. They allow testing components and parts in a rapid and cost-efficient manner without destroying the actual product or changing its surface. Experts from the Fraunhofer IZFP in Saarbrücken will be presenting two exhibits at the Blechexpo in Stuttgart from 7–10 November 2017 that allow fast, reliable, and automated characterization of materials and detection of defects (Hall 5, Booth 5306).

When quality testing uses time-consuming destructive test methods, it can result in enormous costs due to damaging or destroying the products. And given that...

Im Focus: Cold molecules on collision course

Using a new cooling technique MPQ scientists succeed at observing collisions in a dense beam of cold and slow dipolar molecules.

How do chemical reactions proceed at extremely low temperatures? The answer requires the investigation of molecular samples that are cold, dense, and slow at...

Im Focus: Shrinking the proton again!

Scientists from the Max Planck Institute of Quantum Optics, using high precision laser spectroscopy of atomic hydrogen, confirm the surprisingly small value of the proton radius determined from muonic hydrogen.

It was one of the breakthroughs of the year 2010: Laser spectroscopy of muonic hydrogen resulted in a value for the proton charge radius that was significantly...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

ASEAN Member States discuss the future role of renewable energy

17.10.2017 | Event News

World Health Summit 2017: International experts set the course for the future of Global Health

10.10.2017 | Event News

Climate Engineering Conference 2017 Opens in Berlin

10.10.2017 | Event News

 
Latest News

Ocean atmosphere rife with microbes

17.10.2017 | Life Sciences

Neutrons observe vitamin B6-dependent enzyme activity useful for drug development

17.10.2017 | Life Sciences

NASA finds newly formed tropical storm lan over open waters

17.10.2017 | Earth Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>