HIV works by infecting the T-Cells, which are specialized white cells in your body. White cells, of course, are responsible for fighting off infection. When HIV infects T-Cells, it prevents them from doing their job, preventing the immune system from working properly. As a patient's immune system is slowly destroyed, even the commonest of common colds can kill a patient.
HIV, the virus that causes AIDS, enters the T-Cell through a protein receptor called CCR5. Certain people are effectively immune to HIV because they have a genetic mutation that basically results in that receptor not allowing HIV to get through, because its structure is different.
T-Cells are manufactured by bone marrow, where all blood cells are created.
This procedure takes bone marrow from people who are immune to HIV, and plants them into their own bones. From there on, the patient can produce T-Cells that are immune to HIV, allowing their immune systems to work properly.
The problem with this, besides its exorbitant expense, is the problem of tissue grafting.
“It’s not practical and it can kill people,” said Dr. Robert Gallo of the Institute of Human Virology at the University of Maryland, who helped discover the human immunodeficiency virus that causes AIDS.
Tissue grafting is when you take a piece of someone's body (say an organ) and give to another. Heart transplants are a common example of this. But tissue grafting from one person to another is impossible because a person's immune system will recognize the other person's tissue as being an invader, something to destroy, as if it were germs. Your immune system loves to attack anything that isn't yours, no matter if it helps you or not.
Tissue grafting can be done only if the two people's tissues are very similar. The way your immune system recognizes whether something is from your body or not is that it tags it with a marker, like you might tag your luggage at the airport. If the tag looks similar enough, it'll leave it alone. If the tag looks totally different, your immune system brings out the big guns.
So this procedure doesn't really work. And you probably have to be a certain European ethnicity range in order to benefit from it, as the people who are immune to it are mostly Northern European.
So in terms of a practical cure, we're still a long way from one.