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Scientists have long believed that a newborn’s immune system was an immature version of an adult’s, but new research from Cornell University shows that newborns’ T cells (white blood cells that protect against disease ) surpass those of adults in the fight against many infections.
These results help clarify why adults and infants respond differently to infections and pave the way for controlling T cell behavior for therapeutic purposes.
This discovery was described in an article published in Scientific immunology on Feb. 23, co-chaired by Brian Rudd, associate professor of microbiology and immunology, and Andrew Grimson, professor of molecular biology and genetics.
For example, adult T cells outperform newborn T cells in tasks including recognizing antigens, forming immunological memory, and responding to repeated infections, which has led to the belief that infant T cells were simply a younger version of T cells. weak of the adults. But during the COVID-19 pandemic, many were surprised by the apparent lack of illness in babies, calling this long-held belief into question.
Interested in understanding these age-related differences, Rudd and Grimson discovered that newborn T cells are not deficient: instead, they are involved in a part of the immune system that does not require antigen recognition: the innate arm of the immune system. . While adult T cells use adaptive immunity (recognizing specific germs and then fighting them), newborn T cells are activated by proteins associated with innate immunity, the part of the immune system that offers rapid but nonspecific protection against microbes that the body has never found.
“Our paper demonstrates that neonatal T cells are not altered, they are simply different from adult T cells, and these differences likely reflect the type of functions that are most useful to the host at different stages of life.”
Brian Rudd, associate professor of microbiology and immunology, Cornell University
Neonatal T cells may participate in the innate arm of the immune system. This allows newborn T cells to do something that most adult T cells cannot: respond during the early stages of an infection and defend against a wide variety of unknown bacteria, parasites, and viruses.
“We know that neonatal T cells do not protect as well as adult T cells against repeated infections with the same pathogen. But neonatal T cells actually have an enhanced ability to protect the host against the early stages of an initial infection,” he said. Rudd. “Therefore, it is not possible to say that adult T cells are better than neonatal T cells or that neonatal T cells are better than adult T cells. They just have different functions.”
Following up on his discovery, Rudd wants to study neonatal T cells that persist into adulthood in humans. “We are also interested in studying how changes in the relative number of neonatal T cells in adults contribute to variation in susceptibility to infection and disease outcomes,” he said.
This work was supported by the National Institute of Allergy and Infectious Diseases and the National Institute of Child Health and Human Development, at the National Institutes of Health.
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Magazine reference:
Watson, N.B., et al. (2024) The genetic regulatory basis of bystander activation in CD8+ T cells. Scientific immunology. doi.org/10.1126/sciimmunol.adf8776.