Immune System Of Newborn Babies Stronger Than Thought

Contrary to what was previously thought, newborn immune T cells may
have the ability to trigger an inflammatory response to bacteria,
according to a new study led by King's College London. Although their
immune system works very differently to that of adults, babies may
still be able to mount a strong immune defense, finds the study
published in the journal Nature Medicine.

Our immune system is made up of several different types of immune
cells, including neutrophils which play an important role in the
frontline defense against infection, and lymphocytes: B cells which
produce antibodies, and T cells that target cells infected with
viruses and microbes.

Up to now, it was generally believed that babies have an immature
immune system that doesn't trigger the same inflammatory response
normally seen in adults. Although babies need to protect themselves
from the harmful pathogens they are exposed to from birth, it was
thought that their T cells were suppressed to some extent to prevent
inflammatory damage to the developing child. Sceptical of this notion,
the King's-led study set out to characterize the properties of T
cells, examining very small samples of blood in twenty-eight highly
premature babies, as they developed over the first few weeks of life.

The team discovered that whilst T cells in newborn babies are largely
different to those in adults, it is not because they are
immunosuppressed; rather, they manufacture a potent anti-bacterial
molecule known as IL8 that has not previously been considered a major
product of T cells, and that activates neutrophils to attack the
body's foreign invaders.

Dr Deena GibbonsDeena Gibbons, lead author in the Department of
Immunobiology at King's College London, says: "We found that babies
have an in-built anti-bacterial defense mechanism that works
differently to adults, but nevertheless may be effective in protecting
them. This may also be a mechanism by which the baby protects itself
in the womb from infections of the mother. The next stage of our work
will be to better understand the pathways that result in the immune
cells of newborns being so different to those in adults."

This T cell activity could become a target for future treatments aimed
at boosting the immune system of neonates in intensive care, where
infection is a major risk for morbidity and mortality. Premature
babies are also at serious risk of developing inflammatory diseases
such as necrotising enterocolitis (NEC), where severe inflammation
destroys tissues in the gut. NEC is the most common gastrointestinal
surgical emergency in preterm babies, with mortality rates of around
15 to 30 per cent in the UK.