ALL STEM CELLS

JUST when all seems lost, our hero strikes back with such speed that the invader is vanquished. It sounds like the climax to a movie, but if this is how a few people are able to fight off HIV unaided, it could provide a route to a blockbuster drug.
A tiny proportion of people with HIV manage, without drugs, to keep the virus from replicating uncontrollably. We already knew that the immune T-cells of these “elite controllers” react more strongly to HIV than T-cells of other people, but we didn’t know why, says Xu Yu at the Ragon Institute in Boston.
Yu’s team compared the behavior of another part of the immune system, dendritic cells - which “teach” the immune system to destroy infected cells - taken from elite controllers, HIV-negative people, people with HIV receiving drugs, and those not on medication.
Normally, immune cells neutralize viruses by destroying viral RNA and DNA. This is what the team saw in all dendritic cells they infected with HIV – except those from elite controllers. In these cells the virus appeared to run riot, producing copious amounts of genetic material.
“It seemed as though the virus was escaping from detection,” says Yu.
But then came the backlash. When these dendritic cells eventually swung into action, they produced large quantities of antiviral compounds called type 1 interferons, at a much greater rate than other people’s cells.
The elite controllers’ cells were still pumping out interferons two days after infection, long after the other cells’ response had petered out. This triggered the rapid proliferation of T-cells, priming them to attack any cells still infected with the virus (PLoS Pathogens, doi.org/5b8).
Sarah Rowland-Jones at the University of Oxford says the flood of interferon may be triggered by the viral DNA that initially builds up in elite controllers’ cells, making the infection more obvious to the immune system.

Source : New Scientist - 20 June 2015