Hiv Elite controllers

Uno studio dimostra che gli Hiv Elite controllers potrebbero essere tali perche hanno bassi livelli di cellule che sopprimono il sistema immunitario.
Come dire hanno poche cellule che ammazzano le cellule immunitarie colpite dal virus e quindi da distruggere (secondo loro)..
Potrebbe essere questa la chiave?

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HIV Controllers May Have Low Levels Of Cells That Suppress The Immune System
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By Meerat Oza
Published: Feb 10, 2011 3:05 pm

Results of a new study suggest that HIV controllers have unusually low levels of certain regulatory cells that normally suppress the immune system. This, in turn, may lead to a high level of general immune system activation, allowing them to control their HIV.

The researchers suggested that this high level of immune system activation may also be responsible for some of the inflammatory diseases that are more common in HIV controllers, such as thickening of the arteries and a depletion of CD4 (white blood) cells that can cause progression to AIDS even though HIV is suppressed.

HIV controllers are individuals who are infected with HIV but are able to maintain low viral loads (amount of virus in the blood) for extended periods of time without antiretroviral therapy. Also known as HIV long-term non-progressors, they constitute less than 1 percent of the HIV-positive population.

Scientists are interested in HIV controllers because the way in which their bodies avoid HIV disease progression may be key to developing an HIV vaccine or may assist in treating people who have HIV.

Past studies have shown that HIV controllers have unusually high levels of certain white blood cells that help fight infections like HIV.

In this study, researchers hypothesized that this may be because HIV controllers have low levels of a certain type of immune cell called a regulatory T cell. Normally, regulatory T cells suppress the immune system, including other white blood cells, to prevent it from overreacting and damaging the body. This helps keep the immune system in check.

In the case of HIV controllers, the researchers thought that low levels of these regulatory T cells might allow controllers to mount an unusually strong immune response upon infection with the virus, preventing HIV from replicating.

To study this, the researchers compared blood samples from HIV controllers to samples from three other groups: HIV-positive patients who maintained low viral loads by using antiretroviral therapy, HIV-positive patients who did not receive any kind of therapy, and HIV-uninfected patients.

They then measured the levels of various types of immune cells, including regulatory T cells, in the blood samples from each type of study participant.

Results showed that, consistent with previous studies, the HIV controllers had high levels of white blood cells that specifically fight HIV, along with an increased activation of immune cells in general.

However, results also showed that HIV controllers had fewer regulatory T cells than the other groups. Usually when the blood has high levels of white blood cells in it, it should also have high levels of regulatory T cells as a counterbalance to help keep the immune system in check.

Instead, the researchers found that regulatory T cells made up 4 percent of the total immune cells in HIV controllers, 5 percent in HIV-uninfected patients, 5 percent in HIV-positive patients on antiretroviral therapy, and 7 percent in untreated HIV-positive patients.

The researchers noted that the reason for the low regulatory T cell levels, and thus the overall high immune system activation, in controllers is still unclear. They suggested that additional research on the optimal balance between activation and immune suppression may help lead to better HIV vaccine strategies in the future.

For more information, please see the study in PLoS One.