VGTI researchers help uncover why aging reduces immune syste...( PORTLAND Ore. Scientists at the Vacci...),Health

PORTLAND, Ore. Scientists at the Vaccine and Gene Therapy Institute at Oregon Health & Science University have made a discovery that helps explain why our immune system worsens with age. The work was led by Janko Nikolich-Zugich, M.D., Ph.D., a senior scientist at the VGTI. The scientists hope this new information can be used to better protect the elderly from infectious diseases by finding ways to slow or stop the degradation of the immune system. The research results are printed in the current edition of the Journal of Experimental Medicine.

"One of the major components of the immune system are T cells, a form of white blood cell. These cells are programmed to look for certain kinds of disease-causing pathogens, then destroy them and the cells infected by them," said Nikolich-Zugich who also serves as a professor of molecular microbiology and immunology in the OHSU School of Medicine, and is a senior scientist at the OHSU Oregon National Primate Research Center. "Throughout our lives, we have a very diverse population of T cells in our bodies. However, late in life this T cell population becomes less diverse, potentially resulting in a higher level of susceptibility to disease. We think we have found one of the key reasons behind this age-related susceptibility."

Specifically, in old age, the number of CD8 T cells diminishes. CD8 T cells have two functions: to recognize and destroy abnormal or infected cells, and to suppress the activity of other white blood cells to protect normal tissue. The scientists believe that late in life a different kind of CD8 T cell is increasingly produced by the body. These cells, called T cell clonal expansions (TCE), are less effective in fighting disease They also have the ability to accumulate quickly as they have a prolonged lifespan and can avoid normal elimination in the organism.

In the end, these TCE cells can grow to become more than 80 percent of the total CD8 population. The accumulatio
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Contact: Jim Newman
newmanj@ohsu.edu
503-494-8231
Oregon Health & Science University
2-Dec-2004

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