New research from Cornell University challenges the long-held belief that a newborn’s immune system

New research from Cornell University challenges the long-held belief that a newborn’s immune system is merely an immature version of an adult’s. Instead, the study reveals that newborns’ T cells, the white blood cells crucial for disease protection, exhibit superior performance compared to those of adults when combating various infections.

Published in Science Immunology on Feb. 23, the study, co-led by Brian Rudd, associate professor of microbiology and immunology, and Andrew Grimson, professor of molecular biology and genetics, sheds light on why adults and infants respond differently to infections, offering insights for therapeutic interventions targeting T cell behavior.

Contrary to previous assumptions, adult T cells were thought to excel over newborn T cells in tasks such as antigen recognition, immunological memory formation, and response to repeat infections. However, the COVID-19 pandemic raised questions as infants showed surprising resistance to illness.

The researchers found that newborn T cells are not deficient but rather operate within the innate arm of the immune system, which does not rely on antigen recognition. While adult T cells utilize adaptive immunity, recognizing specific pathogens for later defense, newborn T cells are activated by proteins associated with innate immunity, providing rapid but nonspecific protection against novel microbes.

Brian Rudd explains, “Our paper demonstrates that neonatal T cells are not impaired; they are just different from adult T cells, reflecting functions crucial at distinct life stages.”

Neonatal T cells’ participation in the innate immune system grants them the unique ability to respond swiftly during initial infection stages, safeguarding against a broad spectrum of unfamiliar bacteria, parasites, and viruses—an advantage not typically seen in adult T cells.

“While neonatal T cells may not offer the same level of protection against recurring infections with known pathogens, they possess an enhanced capacity to shield the host during early infection stages,” Rudd notes. “It’s not a matter of adult T cells being superior or neonatal T cells being inferior; they simply serve different roles.”

Rudd plans to further investigate neonatal T cells persisting into adulthood and their impact on infection susceptibility and disease outcomes. Supported by the National Institute of Allergy and Infectious Disease and the National Institute of Child Health and Human Development, this research highlights the dynamic nature of immune responses across different life stages.