The forgotten cell
By Kaïla Rosenhek

OTTAWA — One of the first considerations medical professionals take into account when treating patients with human immunodeficiency virus (HIV) is the patient's CD4+ T cell count, as HIV attacks these cells, primarily, using them to duplicate the virus.

Treating HIV is difficult, because it is a lifelong infection, which integrates into a person's genome, making it impossible to eradicate.

While drugs used to treat HIV are very effective, they are also very costly and very toxic. HIV can also develop mutations, allowing it to resist drug treatments. Therefore, new drug treatments must be developed continuously.

A new approach

Dr. Karen Copeland, a scientist at the Ottawa Health Research Institute (OHRI), has spent the last seven years specializing in the study of CD8+ T cells, which serve an anti-viral function, known as cell mediated immunity. She is interested in the inhibitory factors that CD8+ T cells release when fighting an infection.

Her lab has recently invested time looking at the ability of CD8+ T cells to be infected by HIV and how their anti-viral function is affected by the virus.

"The CD8+ T cells can kill cells that are infected with HIV or they can release proteins that can be inhibitory to the virus, so it doesn’t replicate as well," she says.

Copeland has found that certain subsets of CD8+ T cells are more susceptible to infection than others. She has also found that infection of the CD8+ T cell increases its anti-viral function.

"My theory is that HIV probably uses cells bearing the CD4+ receptor in its initial infection, but if the person starts to develop AIDS and the CD4+ T cell count is dropping, then that virus is going to have to adapt itself to affect another type of cell if it wants to stay alive," she says. "I want to prove that the other type of cell is the CD8+ T cell."

HIV, marked by purple spots attached to T cells

If she can find and prove that HIV is entering CD8+ T cells as a different receptor than CD4+ T cells, Copeland says that the receptor could then be targeted for another type of treatment.

CD who?

Overall, she explains, CD8+ T cells are largely ignored in research. The functions of other cells have been studied, but not CD8+ T cells.

Copeland hopes her research of CD8+ T cell's anti-viral factors will encourage people to take a bit more interest in these cells. Some people, however, don't think she should bother looking that closely at CD8+ T cells.

"Very often they’ll just say, 'Who cares! They're CD8+ cells and they're not infected in the body'," she says. "But there are publications out there saying that they are, and some that say that these cells are frequently infected."

Progress holdup

The major challenge for Copeland, like many scientists, is getting money. While the Canadian Institutes of Health Research (CIHR) is currently her main source of funding, Copeland says the Canadian government has not increased HIV research funding since 1993.

"They talk about having increased that money, but a lot of it goes out of Canada and it is not partnered to research here," she says.

Another problem Copeland faces is staff turnover. She's gone through five technicians in the past seven years, which she says restricts her research capabilities.

"It's a big problem, especially here in Ottawa, because if technicians are offered a position within the government at Health Canada for example, they're going to grab it because they'll make a lot more money," she explains. "In research, we can't really pay technicians a huge salary."

In the lead

So far, Copeland says she’s the only person looking at how infection of CD8+ T cells affects their anti-viral function. Other scientists who are in a similar field of research as Copeland are mainly looking at mutant viruses produced by CD8+ T cells in people with AIDS.

But Copeland says she wants to continue to focus on which cells HIV is attaching to first, to target for treatment before AIDS develops.