AUG 04, 2018 01:00 PM PDT

Infant's Innate Immune Response

At birth, a fetus leaves a protected environment that is aquatic, warm, and nearly sterile to the cold external world rich in diverse microbes. In this harsh new world, a baby’s immune system must learn from the many microbes, making use of some while guarding against hostile invaders that might harm. It is a critical transition for an individual and sets a precedent for health or disease in the future.

As a fetus, the immune system must develop to target future pathogens that are currently unknown, while not targeting self and maternal antigens and future friendly microbes known as commensals. In the last three months of pregnancy babies are passed antibodies through the placenta from their mother to convey some level of protection at birth, termed passive immunity, but this immunity will decrease in the first few weeks to months after birth. The infant's gut is initially sterile, but during birth bacteria are passed on to the baby and begin to colonize in the gut, helping to contribute to and teach the baby’s immune system. After birth, as they grow and develop, the immune system will continue to develop as well through vaccination, breastfeeding, infection, and environmental exposure to microbes.

The infant immune system has been seen as “immature,” the ability to tolerate self and maternal antigens were attributed to lack of memory within the immune cells. Basically, the immune system didn’t respond to these compounds because it was too immature to know to respond to them. Now, recent studies show that the infant immune system is more likely a highly regulated, functional, and orchestrated network of competent molecular and cellular components. Infant immunity is a “vigilant establishment” that plays pivotal roles in protecting the developing infant from pathologic conditions such as inflammation while providing defense against infection, not an immature system. A recent review in Frontiers in Immunology focused on understanding innate immunity at a mechanistic level in infants to explore this idea of a functional and component system further.

The innate immune response is the first line of defense against foreign invaders. In an infant, innate immune cells will vary in presence and levels at prenatal, birth, and neonatal stages. Of these cells, most are lowered in activity and frequency compared to their adult counterparts. However, the innate lymphoid cells have higher levels of activity and presence during infancy compared to later stages of life and adulthood. The innate lymphoid cells are a type of immune effector cell that plays a crucial role in host defense, metabolic homeostasis, tissue remodeling, repair, and stem cell regeneration. In infants the innate lymphoid cells appear in the early stages of pregnancy and continue to evolve throughout embryo development, allowing them to potentially affect and be influenced by cellular, molecular and environmental factors. Innate lymphoid cells may play roles in microbiome composition and initiation and regulation of the inflammatory response in infants, helping to adapt and contribute to the immune system from infant to elderly. Infants, starting at the fetal stage, must build up their defenses in preparation for exit from the womb into the world of independent living, but their immune system may not be as “immature” as previously thought.

To learn more about the innate immune response watch the video below!


About the Author
  • Caitlin holds a doctorate degree in Microbiology from the University of Georgia where she studied Mycoplasma pneumoniae and its glycan receptors. She received her Bachelor's in Biology from Virginia Tech (GO HOKIES!). She has a passion for science communication and STEM education with a goal to improve science literacy. She enjoys topics related to human health, with a particular soft spot for pathogens.
You May Also Like
NOV 15, 2019
Drug Discovery & Development
NOV 15, 2019
Glowing Tumors Reveal How Immunotherapeutics Work
In a study published in the Journal of Clinical Investigation, researchers used positron emission tomography (PET) scans to examine how an immunotherapy dr...
NOV 15, 2019
NOV 15, 2019
How a Parasitic Amoeba Evades the Immune System
A parasitic amoeba that causes a gut disease can nibble on host cells and use their proteins. (Image courtesy UC Davis/Hannah Miller)...
NOV 15, 2019
NOV 15, 2019
Opioid Addiction Comes With Increased Risk Of Infection
Public health officials have put decades of work into the battle against infectious diseases. Now, this progress is at risk of being dismantled. A recent s...
NOV 15, 2019
Cell & Molecular Biology
NOV 15, 2019
How Neutrophils are Involved in Gallstone Formation
Gallstones form in the gallbladder, and can be as tiny as a grain of sand or as big as a golf ball....
NOV 15, 2019
NOV 15, 2019
Flu Shot Less Effective Due to Overuse of Antibioitics
New research out of the Stanford University School of Medicine shows that the consequence of overuse of antibiotics lowers the effectiveness of the seasona...
NOV 15, 2019
Health & Medicine
NOV 15, 2019
STDs Still on the Rise in U.S.
Last week, the Centers for Disease Control and Prevention (CDC) released its annual Sexually Transmitted Disease Surveillance Report, the details of which...
Loading Comments...