Bad News for Baby?

          Everyone knows that babies can get sick easily. One infection or virus could be life-threatening. Many babies are strong and healthy at birth, but their bodies seem to lack the ability to protect them from disease. Until recently, it was assumed that babies have weaker immune systems than children and adults. It could be that the immune cells of babies are less developed than those of adults. I thought that seemed like a logical explanation until coming across a new study. Now, scientists at Cincinnati Children’s Hospital Medical Center believe that infant immune cells are not underdeveloped. Rather, they are prevented from functioning by immune-suppressing cells. It seems nearly impossible that the infant immune system evolved to favor cells that prevent immune cells from doing their job of preventing infectious disease. Despite this, researchers have completed a study that supports the theory that infants’ immune systems are being inhibited by a special kind of cell. As scary as it seems that infants may be intentionally vulnerable to any illness, this might not be bad news for baby.

            According to the study, babies do not have immature immune cells, but extra immune-suppressive cells, called CD71+ cells. These special cells eventually develop into red blood cells. CD71+ cells contain the enzyme arginase-2, which helps to repress immune cells. Enzymes are biological proteins within cells that lower the activation energy needed for certain reactions to occur. If arginase-2 is inhibited by other molecules, which means it can no longer function due to a change in structure, its ability to reduce the effectiveness of immune cells is prevented. This also occurs in the presence of the molecule L-arginase. To test this, the researchers used newborn mice and blood cells from umbilical cord blood. In both test subjects, CD71+ cells were found in increased concentrations. They concluded that the presence of these cells allows infants to adapt to the increased stimuli and microbial presence after birth. For example, beneficial bacteria have to colonize in the intestines to aid with digestion, and many other types of bacteria will be present on the skin. If the immune system is not suppressed, the infant experiences increased inflammation in the intestines, and necessary bacteria would not be able to colonize. As the infant grows, the presence of CD71+ declines and the immune system becomes more effective. The researchers concluded that it is most important for the infant’s body to adapt to its environment and to allow bacteria to colonize before it can prevent infection.

            These new findings are intriguing, and can possibly explain trends in infant mortality. In history class, we learned about infant mortality rates throughout time. In the 19^th century, as Americans moved into cities, the likelihood of survival for infants and children greatly decreased. In these urbanized areas, disease was prevalent, due to primitive waste disposal systems and open sewage areas. Maybe the inability of the infant immune system to prevent infection at a young age was a weakness rather than an adaptation in that historical environment. I believe research should be conducted to explain and prevent trends like this.

            In the future, these findings could be used to lower infant mortality, especially in countries where disease control is poor. The researchers intend to explore the possibility of strengthening the infant immune system while still allowing the CD71+ cells to assist in the colonization of bacteria in the intestines. The CD71+ cells could be manipulated or drugs could be used to increase immunity to harmful bacteria. This would change the future of medicine and could improve the outlook for infants who are exposed to disease. I hope to become a pediatrician in the future, so this is especially interesting to me. If doctors could protect newborns from harmful diseases, their job would consist of more active measures of prevention. Instead of telling families to limit their infants’ exposure to people who might carry diseases, doctors could prescribe medicines to protect their bodies. This would allow infants to be around family members and in places such as daycares. Further research could have an interesting impact on medicine and children’s health.

           Though this study is compelling, I question the scientific and ethical issues accompanying the research. The impact of the CD71+ cells was only observed in mice and in umbilical cord blood, not in human infants. Of course, for safety reasons, human newborns cannot be tested, but it might be difficult to compare humans and mice. Humans have a more complex immune system compared to mice, and are exposed to a wide range of disease-carrying microbes. Even with complex trials, it will be difficult to tell how potential medicines or prevention techniques will affect humans. Additionally, the ethical concern over testing on live animals is raised. Before reading this article, I strongly believed that researchers should not use animals – even mice – as test subjects. After reading the study, I have a greater understanding of why it is important to test on the mice. Before administering drugs or new techniques to human babies, it is crucial to know that the method is safe and effective. As long as the testing methods are humane and necessary, I now feel more comfortable supporting testing on animals to ensure the safety of human infants.

            At a time when so much important medical research is being conducted, it is exciting to learn that scientists might be able to combat infectious disease in newborns. The possibilities for this research seem promising, and could impact both patients and professionals in the medical field. It is amazing to think that the most basic unit of life, the cell, can be manipulated to save lives.

Works Cited

Elahi, Shokrollah. "Immunosuppressive CD71+ erythroid cells compromise neonatal host defence against infection." Nature. N.p., n.d. Web. 22 Nov. 2013. <http://www.nature.com/nature/journal/vaop/ncurrent/full/nature12675.html>.

"Immune-suppressing cells explain newborn infection vulnerability." Medical News Today. MediLexicon International, n.d. Web. 20 Nov. 2013. <http://www.medicalnewstoday.com/articles/268394.php>.