Page URL: https://www.bionews.org.uk/page_96051

Fetal immune system is active, not immature

19 June 2017
Appeared in BioNews 905

The fetal immune system is more mature in the second trimester than previously thought, which could assist research into diseases, miscarriage and immune tolerance, researchers say.

Despite being two different organisms, during gestation the mother and fetus are able to co-exist without immune responses being triggered. It had been thought that this was possible because the fetus's immune system was too immature to mount a response to material crossing over from the mother during pregnancy.

But the new study showed that the fetal immune system is present and functioning as early as 13 weeks gestation, and can operate independently from the mother. Like the adult immune system, the fetal system is able to identify foreign proteins. However, unlike the adult system the fetal immune system is much less likely to attack foreign human cells, which may explain how the fetus tolerates its mother.

The insight 'lays the foundation for future immune-directed therapies, and contributes to our knowledge of the fetal origins of certain pregnancy-associated conditions, such as pre-eclampsia,' said joint senior author Professor Jerry Chan of the KK Women’s and Children’s Hospital, Singapore. The scientists say it may also help to understand and limit gestational diabetes and miscarriage. 

The findings could also help to understand certain immune mechanisms in adults. 'Some of the events that occur during development might be important [in adult disease] and now the fetal immune system is part of this equation', said joint senior author Dr Florent Ginhoux of the Agency of Science, Technology and Research, Singapore.

Organ transplants and cell-based therapies are often unsuccessful due to immune rejection responses in patients receiving them; this research could help to find way to suppress immune responses in these situations.

Tissue was collected from fetuses between 12 and 22 weeks gestation for the study, published in Nature. The researchers identified and characterised immune cells that were present in the tissue.

They found that functional dendritic cells were present by 13 weeks of gestation. These cells act as sentinels - helping the body to determine which foreign substances should be destroyed, and recruiting other immune cells accordingly.

In the lab, these fetal dendritic cells behaved largely in the same way as adult dendritic cells. However, fetal dendritic cells suppressed immune responses to foreign human proteins, while dendritic cells from adults were more likely to mount a response to destroy them.

Professor Mike McCune of the University of California, San Francisco, who did not participate in the work told The Scientist: 'Now that we understand how tolerance works in the fetus, can we apply that to situations in the adult where tolerance might be important?'

SOURCES & REFERENCES
Breakthrough findings establish fetal immunity develops as early as second trimester of pregnancy
KK Women's and Children's Hospital |  15 June 2017
Eye-opening picture of fetal immune system emerges
Nature News |  14 June 2017
Fetal Immune System Operational by Second Trimester
The Scientist |  14 June 2017
Human fetal dendritic cells promote prenatal T-cell immune suppression through arginase-2
Nature |  14 June 2017
RELATED ARTICLES FROM THE BIONEWS ARCHIVE
4 June 2018 - by Dr Nicoletta Charolidi 
The first in utero stem cell transplant trial has welcomed its first baby - born after being treated in the womb with her mother's stem cells...
9 November 2015 - by Dr Norman Shreeve 
In recent years a range of treatments aimed at suppressing uterine natural killer activity have sprung up, but this has no scientific rationale and can have significant and dangerous side effects...
19 January 2015 - by Kirsty Oswald 
A twin study has shown that the majority of variation in immunity between individuals is due to non-genetic factors.
3 December 2012 - by Chris Baldacci 
A man may contribute more than just sperm to the process of conception, research suggests...
28 March 2011 - by Owen Clark 
A study has linked mutations in three genes with the severe pregnancy condition, pre-eclampsia. The international research team say they're the first to link genetic mutations and pre-eclampsia in women with the autoimmune disorder lupus...
HAVE YOUR SAY
Log in to add a Comment.

By posting a comment you agree to abide by the BioNews terms and conditions


Syndicate this story - click here to enquire about using this story.