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
JUL 09, 2018
Immunology
JUL 09, 2018
Protein Complex Determines the Fate of T cells
The protein complex mTORC1 has been shown to integrate metabolic and signaling activity to determine the fate of T cell lineage between alpha beta and gamma delta....
JUL 16, 2018
Immunology
JUL 16, 2018
T cells and the Need for Speed
A recent study has shown that T cell receptors are dispersed across the T cell surface, as opposed to clustered, to allow for a rapid immune reaction....
JUL 19, 2018
Microbiology
JUL 19, 2018
Mom's Microbiome has a Big Impact on Kid's Autism Risk
For many years, scientists have been trying to learn more about the causes of autism....
AUG 25, 2018
Immunology
AUG 25, 2018
Maternal Depression Alters Mom and Baby's Immune Markers
Maternal depression alters stress and immune system biomarkers in children leading to social withdrawal and behavioral problems....
AUG 24, 2018
Cell & Molecular Biology
AUG 24, 2018
Chronic Allergies can Change Cells
Chronic rhinosinusitis is different from allergies; it leads to serious inflammation and swelling in the sinuses that can last for years....
SEP 04, 2018
Immunology
SEP 04, 2018
Development of Damaging Immune Cells in Tuberculosis Infection
Development of damaging white blood cells occurs during Tuberculosis infection leading to a maladaptive immune response....
Loading Comments...