Research shows that a baby’s immune system is stronger than we think

Babies' immune systems may be tougher than we first thought

New research shows that an infant's T cells—white blood cells that protect from disease—outperform those of adults at fighting off numerous infections.

The results help to explain why adults and infants respond differently to infections.

It also paves the way for further research into how we can potentially control T cells behaviour for therapeutic applications.

This discovery was described in a paper published in Science Immunology, co-led by Brian Rudd, associate professor of microbiology and immunology, and Andrew Grimson, professor of molecular biology and genetics.

When compared to adult T cells, the newborn T cells outperform them at tasks including recognising antigens, forming immunological memory and responding to repeat infections, which has led to the belief that infant T cells were just a weaker version of the adult ones.

It was during the COVID-19 pandemic that many people were surprised by the apparent low levels of illness in infants, causing scientists to question what was established as fact.

Interested in understanding these age-related differences, Rudd and Grimson discovered that newborn T cells are not deficient.

While adult T cells use adaptive immunity—recognising specific germs to then fight them later—newborn T cells are activated by proteins associated with innate immunity.

"Our paper demonstrates that neonatal T cells are not impaired, they are just different than adult T cells and these differences likely reflect the type of functions that are most useful to the host at distinct stages of life,” said Brian Rudd, associate professor of microbiology and immunology at Cornell.

Neonatal T cells can participate in the innate arm of the immune system.

This enables newborn T cells to do something that most adult T cells cannot: respond during the very first stages of infection and defend against a wide variety of unknown bacteria, parasites and viruses.

Following up on the discovery, Rudd said he wants to study the 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 the susceptibility to infection and outcomes to disease," he said.

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