Newborn T cells were found to excel in immune defense

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-lymphocytes – white blood cells that protect against disease – outperform adults’ in fighting 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 applications.

This discovery was described in an article published in Science Immunology on February 23, led 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 at tasks such as recognizing antigens, forming immune memory, and responding to repeated infections, which led to the belief that infant T cells were simply a weaker version of the adults. But during the COVID-19 pandemic, many were surprised by the apparent lack of illness in infants, calling that 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 engage 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 microbes to fight them later—newborn T cells are activated by proteins associated with innate immunity, the part of the immune system that offers quick but nonspecific protection against microbes it hasn’t encountered. never the body.

Our work demonstrates that neonatal T cells are not impaired, 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 can participate in the innate arm of the immune system. This allows newborn T cells to do something that most adult T cells cannot: respond to the very 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 from the early stages of an initial infection,” said Rudd. “So it’s not possible to say that adult T cells are better than neonatal T cells or neonatal T cells are better than adult T cells. They just have different functions.”

Following on from 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 numbers of neonatal T cells in adults contribute to variation in susceptibility to infections 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.