As people age, their immune systems decline. But a new study suggests a way to rejuvenate immune function: Stimulating the liver to produce some signals ordinarily generated by the thymus can reverse age-related declines in T-cell populations.

MIT and Broad Institute researchers found a way to overcome age-related immune system decline by temporarily programming liver cells to take over the maturation of T cells. Using mRNA, the researchers were able to rejuvenate the immune system, in a study of mice.