Newborn immune systems can fight threats early, Yale study finds

While some think that newborns’ immune systems are weaker versions of their adult forms, results of a recent study led by Yale researchers show that newborns’ immune systems are highly specialized and ready to face threats that can appear early on in their developments. 

The team’s work examined naïve CD8+ T cells, a type of white blood cell in immune systems that has not yet encountered infection and that plays a critical role in newborn immune response to viruses and cancers. 

“Contrary to the common belief that newborn immunity is immature, we found that these cells are actually ‘primed and ready,’” Nina Noa Brodsky, the first author of the study and an assistant professor of pediatrics at the School of Medicine, wrote to the News. “Within hours of sensing a threat, they rapidly activate, ramp up glycolytic energy use, and release inflammatory molecules that help fight infection.”

While the cells are quick to take action, Brodsky also noted that their responses are fleeting by design because many CD8+ T cells die shortly after activation to avoid harming developing organs with unwanted inflammation.  

Brodsky also said that some of the inspiration for the project came from her work in the clinic as a pediatric critical care physician.

“I frequently care for infants and young children facing severe infections and inflammatory complications, yet the underlying mechanisms driving these outcomes remain incompletely understood,” Brodsky wrote.

According to Brodsky, the research team aimed to improve understanding of how immune systems are programmed in newborns to protect them during the transition from the uterus to a world filled with microbes and harmful pathogens. 

“This research has been both challenging and rewarding, made possible through strong collaborations and advanced laboratory techniques,” Brodsky wrote. “It is gratifying to uncover new insights into this critical stage of immune development and to pursue the important questions that have emerged from these findings.” 

Brodsky emphasized the difficulty of navigating the high variability of human cells in her research and working with a variety of data to characterize the different regulatory factors that guide the cells to switch on and off. 

For Brodsky, the study pioneered a new perspective on the power of infant immunity. The presence of CED8+ T cells that are “uniquely programmed” to quickly fight off threats demonstrates that infant immune systems are not less developed than their adult counterparts; rather, they are just wired to respond differently to infection. 

The findings of the study could pave the way for the development of new vaccines and therapies, Brodsky added.

One of the team’s main goals for the future is to study the development of the immune response throughout the early years of life in healthy children and children with severe viral infections or inflammatory complications.

Dinesh Babu Uthaya Kumar, a co-author on the study and a researcher at the School of Medicine, shared that the research team hopes to investigate the role of CED8+ T cells in responding to infections like RSV and influenza by modeling early-life viral infections. 

“From my perspective, this work represents an important first step toward harnessing the potential of neonatal CD8 T cells—not only during infancy but also later in life,” Uthaya Kumar wrote in a statement to the News. “Their rapid yet short-lived response strategy may have unique advantages in certain disease contexts, especially where prolonged activity of killer cells could lead to unwanted inflammation or autoimmune complications.”

Uthaya Kumar added that the study might also shed light on why some babies are more susceptible to certain infections or inflammatory conditions, which could serve as the basis for improving care and treatment procedures. 

“This work contributes to our understanding of the unique nature of the immune system in early life, which is not only important in childhood but also represents a critical developmental window that can have implications for health later in life,” Anis Barmada GRD ’29, another co-author and a fellow at the School of Medicine, wrote to the News. 

The Department of Immunobiology is located at the Anlyan Center at the School of Medicine.