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By Ginger Hall Carnes
As we get older, we make fewer new T cells, which are white blood cells critical for the proper functioning of the immune system. That means we are more susceptible to infection and do not respond as well to vaccines.
One researcher’s aim is to understand the way the thymus works because that is where T cells develop. And she has developed a novel method to study the stromal cells that reside in the thymus and could be the key to producing more of those critical T cells.
Ann V. Griffith, Ph.D., who joined the medical school in January 2015 as assistant professor in the Department of Microbiology, Immunology and Molecular Genetics, said not many people are focused on this question because it is so difficult to isolate these cells. Most research has been focused on the lymphocytes, or T cells, because they are more abundant and easier to isolate. Isolation methods for the stromal cells take several hours, “change the biology of the cells because they induce stress and are relatively inefficient,” she said.
However, Dr. Griffith and her colleagues have developed a method through a grant from the National Institutes of Health that takes less time. “We snap-freeze thymus tissue so there are no changes induced by isolation. We make sections and look through the microscope, micro-dissect regions of the whole tissue, and then easily sort out the corresponding lymphocytes using flow cytometry.”
Dr. Griffith, who received her bachelor’s from The University of Texas at Austin and her master’s and Ph.D. from the UT Health Science Center at Houston, said they are focusing on how the stromal cells direct T cell development and also how they change with age.
“One of the earliest and most profound changes that you see with aging is the atrophy of the thymus. It becomes very small, starting around the time of puberty. The decline in the size of the thymus means you’re producing fewer and fewer new T cells. We know that atrophy that happens with aging is really driven by changes in the stromal cells; the T cells don’t change much until much later in life,” she said. Because of the relationship with aging, Dr. Griffith works with the Barshop Institute for Longevity and Aging Studies in her research.
Another advantage of being in San Antonio is being able to partner with University Hospital. Working with the nearby hospital allows her to strengthen grant applications. “Our funding agencies always want to see that what we’re doing has an impact on human health,” she said. “By working with clinicians, we really can ask if what we’re seeing in our mouse models is truly relevant to humans.”