Mayo Clinic researchers have discovered a way to dramatically boost the output of immune system cells from the thymus, which may lead to improved cancer vaccines, as well as to ways to otherwise strengthen immune responses.
The Mayo report appears in the current online edition of the journal AIDS. Mayo Clinic scientists studied the immune system responses in blood samples from health care workers accidentally exposed to HIV, who then received a commonly used anti-AIDS treatment known as antiretroviral therapy (ART). None of the workers developed HIV infections.
In these non-HIV-infected test subjects, the scientists discovered that ART dramatically increases (up to a factor of 1,000) the production of cells from which the immune system makes disease-attacking T cells. Importantly, the increase in T cells also occurred in older people who generally produce few new T cells. Further experiments were performed in mice to see if the ART treatment caused the immune system to erroneously attack the host instead of disease agents. It did not.
The findings are significant because they suggest new ways to use an existing and approved drug regimen of ART to stimulate the thymus to produce more T cells -- without provoking an "autoimmune" reaction in which the body attacks itself. T cells are major disease fighters of the immune system that are depleted in diseases such as AIDS and cancers, as well as in bone marrow transplant recipients. ART is a combination treatment of antiretroviral drugs and drugs that prevent cell death.
"One of the potential uses we envision is to use the ART treatment as a way to use tumor components to immunize cancer patients against their own cancer cells," explains Mayo Clinic immunologist David McKean, Ph.D. "The current problem with this treatment strategy is that the tumor gives off a variety of soluble products which we don't fully understand, but which we know wreck havoc on the immune system by suppressing its various components. If we can use the ART drugs to increase the number of newly produced T cells in cancer patients first, we can potentially improve the likelihood of getting a cancer vaccine to work."
The findings may also benefit the aging population.