When it comes to the immune system of newborns, popular belief holds that their immune cells are weak, making them more prone to infection. But a new study from Cornell University in New York, NY, suggests that an infant's immune system is actually stronger than that of adults; it just has a short memory.
The research team, led by Brian Rudd of Cornell's College of Veterinary Medicine, recently published their findings in the Journal of Immunology.
The immune system is made up of a network of cells, tissues and organs that protect against pathogens, such as bacteria and viruses.
It is well known that in the first few months of an infant's life, their immune system is unable to stave off infection as effectively as an adult immune system. But the reasons behind this are not fully understood.
The strength of an individual's immune system depends on the formation of "memory T cells," according to the Cornell team. These T cells remember pathogens they have previously encountered so that the next time they enter the body, they can respond to them quickly and effectively.
Adults create a large number of memory T cells during infection. Approximately 10% of these settle in a "long-lived memory pool," ready to fight the next time a pathogen enters the body.
Infant T cells do not enter memory pool
The researchers found that infant immune systems created T cells that responded to infection faster and stronger, but these cells were short-lived and did not make it into the memory.
However, the results of the team's study revealed that the same process does not happen in an infant's immune system.
When stimulating adult and infant immune systems with the same infection, the researchers found that the infant immune system created T cells that responded faster and with more strength, but these cells were short-lived and did not make it into the memory pool.
"So the immune system is forced to start the learning process over again when infected by the same pathogen later in life," explains Rudd.
The team believes this discovery paves the way for the development of new immunizations that could protect infants and children from infectious diseases. Rudd says:
"The perfect vaccine would be a single dose given at birth that generates long-lasting immunity.
No such vaccine exists because we haven't understood why infants rapidly lose immunities. Our finding could change the way we immunize infants and ultimately lead to more effective ways of enhancing immunity in early life."
He adds that the team hopes to conduct further studies and find a way to make infant cells act like adult cells so they can learn from vaccines and respond to infection.
Last year, Medical News Today reported on a study from Cincinnati Children's Hospital Medical Center, which suggested that immune-suppressing cells may be a cause of infection vulnerability in newborns.
For their study, the researchers extracted immune system cells from adult mice and transferred them into newborn mice to see if this would boost their immunity when exposed to infection.
The team found the adult cells in the newborn mice did not produce protective immune system cytokines, so their immune system was not strengthened. However, on transferring immune system cells from adult mice into newborn mice, the newborn cells created protective cykotine TNF-alpha, which helps boost the protective response of the immune system against infection.
"Our findings fundamentally change how we look at neonatal susceptibility to infection by suggesting it is caused by active immune suppression during this developmental period, as opposed to the immaturity of immune cells," says study author Sing Sing Way.