Welcome to our science-like weekly feature, "Hey, Science," in which we will have our most provocative scientific questions answered by real live scientists (or related experts). No question is too smart for us to tackle, theoretically speaking. This week, experts address a Gawker reader's wacky theory: Can massive blood transfusions be used to treat AIDS?
THE QUESTION: This question comes from inquisitive reader Michael, who asks, "Could you cure, or at a minimum delay the effects of, the AIDS virus by simultaneously drawing infected blood and transfusing in 'clean' blood into the patient? You would still have tainted blood in the system, but wouldn't this turn the clock back a bit in regard to how much of the virus is in the person's blood stream?" What say you, doctors—can EXTREME blood transfusions fix HIV?
Not a bad question actually. [Ed.: Sweet] The issue is that the virus infects T cells and these reside both in the blood and in tissues, such as the lymph nodes and the gastrointestinal tract. So even if one were to entirely rid the blood of the virus (which would be really difficult to accomplish), there would be other sites such as those I mention that would still have "reservoirs" of virus. Add to this the difficulty and potential complications of doing the blood exchange, which is done for certain other conditions... And you have a sufficiently bad benefit/harm ratio to make the procedure untenable.
Evidence for most infectious disorders is detected in the blood. This does not mean that the blood is the location of the infection. In the case of HIV, most / all of the virus replication occurs in lymphoid tissue (gut, spleen, lymph nodes), NOT in the bloodstream. Blood is simply a place were we can readily detect it. And while blood can transmit HIV, it is because the virus is present in blood not because it is replicating there. Therefore, removing 'infected' blood and replacing it with 'clean' is like taking a cup of water from the ocean and then pouring in a cup of fresh water in the hopes you would make the ocean a very large freshwater lake!
The short answer is that it wouldn't work. HIV is a retrovirus and, as such, integrates it's reverse transcribed DNA into the host cell genome. That DNA will sit dormant in a lymphocyte until the cell dies. as such, there will be plenty of cells that contain HIV DNA sitting around, not just in the blood stream, but in the tissues, most notably the intestines. Even if you could replace all of the peripheral blood through transfusion, additional lymphocytes would be in the tissues and would continue to produce virus, which would just infect the cells that you have transfused in.
I can think of a few reasons why the approach you mentioned would not work, including that HIV infection is not a process that is confined to the intravascular space (meaning inside the blood vessels). The tissue through which the infection gained access to the body (needle stick, mucous membrane) would be contaminated with virus as would the regional lymph nodes, which drain these tissues. So exchanging the blood volume wouldn't purge the body of the virus.
There is no way to delay the effects of AIDS by removing infected blood and transfusing in uninfected blood. HIV replicates predominantly in a type of lymphocyte called a CD4+ T cell, or a helper T cell. About 2% of the CD4+ T cells in our bodies are circulating in the blood. The rest are in our intestines or in lymph nodes scattered around our body. Therefore, even if we could remove all of the HIV infected lymphocytes in our blood, the vast majority of the cells infected by HIV would not be removed, and HIV would still be reproducing in those cells.
Hope that is understandable. [Ed.: lol]
THE VERDICT: No, you can't cure (or even ameliorate) HIV/ AIDS with blood transfusions, because the virus hangs out elsewhere in the body, and would just reinfect the new blood. Don't you think they would have tried that already?