T cells, biology textbooks teach us, are the soldiers of the immune system, constantly ready to respond to a variety of threats from viruses to tumors. However, without rest and maintenance T cells can die and make their hosts more vulnerable to pathogens, Yale scientists report May 27 in the journal science,
“We may have to change how we teach T cell biology,” said Leiping Chen, a United Technologies Corporation professor of cancer research and professor of immunobiology, dermatology, and medicine at Yale and the study’s senior author.
T cells remain in a dormant state until pathogens are detected. However, the molecular mechanisms that keep T cells inactive were previously unknown.
In the new study, Yale researchers show that a protein known as CD8a — which is found in a subset of T cells called CD8 cells — is important for keeping cells in this dormant state. When the scientists removed this protein in mice, the protective CD8 cells were unable to enter a quiescent state and died, leaving the host vulnerable to infection.
In addition, they identified another protein, PILRA, which provides a biochemical signal to CD8a. By disrupting this protein pairing, both “memory” CD8 cells — cells previously exposed to pathogens — and naive cells died because they lacked the ability to remain in a quiescent state.
Researchers hope that understanding why this resting state is important for the maintenance and survival of T cells may improve immune system function.
Chen noted that as people age, they lose both naive and memory T cells, making older individuals more vulnerable to infection. The authors suggest that it is possible that the inability of T cells to remain in a silent state may make people more vulnerable to infection and cancer.
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material provided by Yale University, Original written by Bill Hathaway. Note: Content can be edited for style and length.
