Medical researcher studying effect of HIV on the immune system

By Sharon Gray

In a small, specialized laboratory at Memorial's medical school, Dr. Michael Grant works with HIV-infected blood to discover how immune cells die.

It's complicated work that requires a specially-equipped laboratory to prevent any contamination. In a separate anteroom, Dr. Grant dons a special gown before proceeding through a self-closing door into the Level 3 lab, where negative pressure is maintained and air is drawn outside. Other features include impervious flooring material and sealed light fixtures. Inside this laboratory, Dr. Grant is studying the effect HIV has on the immune system by looking at two classes of blood lymphocytes, the CD8s and the CD4s.

In HIV-infected individuals, the CD4 lymphocytes disappear, while the number of CD8 killer cells increase. "I've worked to try and see what role CD8 killing activity might have in the progression of AIDS. I wanted to see what molecules on the killer cells and the helper cells were involved in triggering the killing cell and what the killer cell was recognizing on the target cell," said Dr. Grant, who began this work while doing doctoral graduate work at McMaster University.

After completing his PhD, Dr. Grant moved to Vancouver and worked with a company that licensed a monoclonal antibody that he discovered would selectively block the killer cells that destroyed uninfected CD4 lymphocytes. This monoclonal antibody is now being tested at Harvard University on Simian Immuno-Deficiency Virus- infected monkeys. Now at Memorial, Dr. Grant is continuing research on this battle of blood lymphocytes.

"The consensus is emerging that the CD4s that are disappearing aren't infected with HIV but are disappearing by an indirect process triggered by HIV which leads to them committing suicide. We're now looking at the conditions under which they commit suicide, and what role the CD8 killers might play in triggering suicide."

While Dr. Grant doesn't work directly on HIV/AIDS therapies, he says that new therapies are dealing with the very biological molecules produced by the CD8 lymphocytes that he is studying. "We know it's important to distinguish different subsets of CD8s and delineate which are pathological and which are beneficial."