AUG 21, 2017 11:53 AM PDT

Blood-Filtering Organs: The Third Line of Defense Against Pathogens

WRITTEN BY: Kara Marker

We often think of antibodies and vaccines when we talk about viral infection, but there’s another part of the immune system that works to fight viruses before antibodies enter the picture. Within this part, called the innate immune response, scientists are discovering a third “checkpoint” where immune cells attack viruses to prevent them from spreading to the rest of the body.

One role of the innate immune system is to quickly block the spread of infection. It was once believed that white blood cells, called macrophages, destroy viruses at the site of an infection, like a mosquito bite. Credit: Penn State

At first, immune cells called macrophages meet a virus as soon as it enters the body. The viruses that escape the first battle make their way to the lymph nodes for round two. Past studies suggested the innate immune system battle ended here, that the more specialized adaptive immune system took the reins with antibodies intricately designed to attack the specific virus. However, in a new study from Penn State, scientists found that there is one more attack led by the innate immune response, and it occurs in blood-filtering organs such as the liver and spleen.

Not only is there indeed a previously-unrealized third checkpoint by the innate immune system during viral infection, but it appears that this checkpoint is the most important. "If you have a deficit in immunity in those organs, it's actually much worse than if you have a deficit in the local lymph node," explained Christopher C. Norbury, who led the study. "This means even something as small as a pin prick in the skin still involves a response in your entire body."

Norbury and his team of scientists made this discovery by studying mice models of infection. They were altered to be lacking different types of myeloid cells, the descendants of macrophages and other immune cells like neutrophils, basophils, and eosinophils, in each of the three different checkpoints. Afterward, they were infected with poxvirus. Lacking macrophages in the third checkpoint, the liver and spleen, had the biggest impact on poxvirus spreading to the rest of the body.

If depletion of macrophages in the spleen or liver limits the body’s ability to fight infection, boosting numbers of these immune cells might counteract this effect. Additionally, the study scientists suggest, they could look for similar depletions in certain populations that could explain select vulnerability to viral infections.

In light of the discovery, Norbury admits the he isn’t sure yet how he and his team would boost macrophages levels in the liver and spleen or what the side effects would be. If anything, he says, “maybe people will turn their attention to these cells now."

The present study was published in the journal PLOS Pathogens.

Sources: The International Journal of Biochemistry & Cell Biology, Penn State

About the Author
  • I am a scientific journalist and enthusiast, especially in the realm of biomedicine. I am passionate about conveying the truth in scientific phenomena and subsequently improving health and public awareness. Sometimes scientific research needs a translator to effectively communicate the scientific jargon present in significant findings. I plan to be that translating communicator, and I hope to decrease the spread of misrepresented scientific phenomena! Check out my science blog: ScienceKara.com.
You May Also Like
OCT 21, 2019
Microbiology
OCT 21, 2019
Gut Microbes may Link Stress and Autoimmune Disease
Stress can have a detrimental effect on our health, and appears to contribute to the development of autoimmune diseases....
OCT 21, 2019
Microbiology
OCT 21, 2019
Healthy Fat From a Beneficial Microbe May Help us Relieve Stress
We may one day be able to use a 'stress vaccine' to ward off the damage caused by traumatic events....
OCT 21, 2019
Health & Medicine
OCT 21, 2019
Rare Bone Marrow Manifestation in Sarcoidosis
Sarcoidosis is an inflammatory disease with the hallmark diagnostic feature being non-caseating granulomas--clumps of immune cells including macr...
OCT 21, 2019
Health & Medicine
OCT 21, 2019
Blood-Brain Barrier Impairment and Its Role in Alzheimer's Disease
In healthy people, the blood-brain barrier (BBB), which is fromed by brain endothelial cells, strictly controls the entrance of harmful materials into...
OCT 21, 2019
Immunology
OCT 21, 2019
New Observations of a Cancer Transcriptase
New research shows a transcriptase that helps time cell death varies in expression, and is unusually localized, in cancer cells.  The transcriptase, T...
OCT 21, 2019
Immunology
OCT 21, 2019
Researchers Identify Pair of "Recruiters" that Pull T Cells to the Lungs
How do CD8 T cells make it to the lungs to help in the fight against infection? Why don’t T cells remain longer in the lungs? How can science optimiz...
Loading Comments...