A new type of cell that can be infected by HIV-1, the AIDS virus, has been found.

These cells belong to the group of Natural Killer (NK) cells. Unlike other NK cells, they express on their surface the receptor molecules that allow infection by HIV-1.

The new work also shows that NK cells are infected in patients and remain infected despite antiretroviral treatment. This makes the NK cells a long-term reservoir for the virus.

These results are of interest to people that want to purge the virus from the body. They are also of interest to those studying the innate immune system and the function of NK cells in general, and the role of the innate system in AIDS.

In the long run, good news. We know a bit more about the cells infected by HIV in the body. The better we know the enemy, the more chances we have to defeat it.

No, there are several known reservoirs for HIV. The NK cells, like the T cells is a place that the virus is found persistently. Therefore, special attention needs to be paid to these reservoirs.

We know that NK cells are substantially different than T cells. It is prudent to study them more and learn exactly how they behave.

We know also that many NK cells have high levels of the drug exporter protein p-glycoprotein, and that they are more resistant to drugs because of it. This may be important for the AIDS virus infection.

We know that HIV infection affects the NK cells. One very important question is how this infection affects the function of the innate immune system, of which NK cells is an essential part. The innate immunity in AIDS certainly needs to be studied more.

The conclusions suggest that these cells need to be studied further to find ways to eliminate the virus. We need to know in more detail how long the cells leave, how they circulate in the body, and how are they affected by anti-retroviral drugs.

There are two possibilities, and we do not know which one or combination thereof applies: Either the NK cells live long, or they are infected continuously despite the anti-retroviral therapy. The answer to this question is important for developing methods to improve therapy.

Any practical application of these results is years away. Patients should follow the advice of their physicians, who know them best and can apply any future therapy improvements.

The AIDS virus needs the surface receptor CD4 in combination with a second receptor, either CCR5 or CXCR4, in order to infect human cells. If the combination of these receptors is not on the surface, then there is no infection.

The AIDS virus infects CD4+ T lymphocytes, monocytes, and other cells that have the appropriate surface receptors (CD4 and CCR5 or CD4 and CCR4). It infects also NKT cells, which are T cells with some NK characteristics. In contrast, the CD4+ NK cells described in the present work do not appear to have any T cell characteristics. The function of the new cells is not fully known.

The innate immune system involves the most ancient sets of mechanisms for self/non-self recognition and defense against invaders. The innate immune system provides the first line of defense and cross-talks with the adoptive immune response (i.e., development of antigen-specific antibodies and T cells).

NK cells are an essential part of the innate immune system and are known to be important for fighting cancer and viral diseases.

Dysregulation of the innate immune system after HIV infection has been reported and may have important consequences for AIDS development. We have found several changes in the cells associated with innate immunity in AIDS patients. Infection of the CD4+ NK cells may be the reason for some of these changes.