What is Killing Off T Helper Cells and other info

[tednlou2]

I was reading the news updates on thebody.  I came across a couple things I thought were interesting.  The first was about how HIV damages our bodies.  I thought I basically knew how the damage is done.  I was particularly interested in the info under Number 6.  I didn't know our CD8 cells actually kill off good cells unaffected by HIV.  The article explains it much better than I. 

6. What Is Killing Off the T Helper Cells?
It has been known for a long time that the T cells (the "killer" T cells) -- whose job it is to kill off infected cells -- also kill off uninfected cells that look a lot like the infected ones. We might call them 'bystander' T cells. Scientists call the killer T cell a 'CD8+ cytotoxic lymphocyte' and these cells become hyperactive when HIV is around. In fact, they become so hyperactive, that for every cell actually infected with HIV, they kill hundreds or thousands of uninfected T helper cells and they slowly reduce your total healthy cell repertoire. It is actually this overkill from hyperactive CD8 cells that causes you to get AIDS, not the actual virus.

[A technical note: In the early 1990s, the researchers Joyce Zarling, Leonard Adelman and Allen D. Allen, working independently, proved to a scientific certainty that it was the cytotoxic CD8 T cells that were indiscriminately killing off CD4 T cells. This was published in prominent medical journals, such as Journal of Immunology, AIDS, etc. and led Allen to invent an agent known as Cytolin (a mouse anti-human monoclonal antibody.]




7. How Could We Stop This From Happening?
Your killer defense CD8 T cells would calm down if the amount of HIV in your body would be reduced. This is what antiretrovirals (the medicines that stop HIV from making more HIV) accomplish. However, there are several problems with this approach, even though it has worked wonderfully keeping millions of people alive for many, many years.

The problems are: the HIV medicines are expensive, have side effects and the virus can sometimes get resistant to them.

For this reason, it would be useful to have a medicine or a group of medicines which the virus would not get resistant to, which are not too expensive and which would help calm down the killer cells a little.

Different chemicals like steroids act like a brake on the immune system, and a particular monoclonal antibody called "Cytolin" (mentioned above) acts like a brake on the hyperactivity of the CD8's -- it calms them down. It down regulates their hyperactivity, which would help the body keep healthy T cells around to do their work preventing opportunistic infections, and therefore avoiding AIDS.

We have known for some time that this approach of calming down the immune system would work to slow down AIDS because we have had medicines that calm down or slow down the immune system. There are immune tranquilizers, such as cyclosporine A for example, which makes CD8s less panicky and lets them shoot at the enemy with an accurately pointed pistol instead of what is more like a machine gun shooting down every cell that is near an infected T cell.

When you use these types of drugs on people with HIV, you can show that T cells are no longer being killed off and the amount of virus is actually reduced.

However these early immune tranquilizers were just as over reactive as the CD8 cells we are trying to calm down, and made the immune system unable to protect us from many illnesses.

But now there are some drugs known as 'immune modulators' that make the killing CD8 cells less hyperactive, but allow them to still kill off the already infected cells, and allow them to still protect against other infections as the body gets attacked.

One of these immune modulators, mentioned above, is called "Cytolin." It is what scientists call a 'monoclonal antibody' and it makes the killer cells less crazy -- that is, less likely to kill off all the cells near an infected cell but instead focuses just on the infected cell.

During the height of the AIDS pandemic, before the antiviral cocktails were available, activist doctors used Cytolin to rescue a few hundred patients. [Data from 188 patients treated with Cytolin for 18 months were reported to the FDA (check www.searchforacure.org). A Phase I(b)/II(a) study of Cytolin was reported at the 2002 and 2005 CROI national conferences by Donald W. Northfeld, MD.]

Cytolin -- which is given as an intravenous infusion -- is being developed by a west coast company called CytoDyn and is being studied by Eric Rosenberg, M.D., a researcher at the Massachusetts General Hospital. It is hoped that within a year we can get more information on how the medicine works on people with HIV.

For those of you who haven't already read the article:  http://www.thebody.com/content/art55284.html

The article goes into more interesting info. 

[tednlou2]

"It is actually this overkill from hyperactive CD8 cells that causes you to get AIDS, not the actual virus."

I thought this was very interesting and something I didn't know.