New discovery on early immune system development

November 12, 2013

Researchers at Lund University have shed light on how and when the immune system is formed, raising hope of better understanding various diseases in children, such as leukaemia.

The immune system is complex and a number of genetic diseases are attributed to defects in the cells that form its origins. The study from Lund and Oxford University presents unique findings on the formation of these cells.

We know that the first blood stem cells are formed in the aorta region and then travel to the liver, which is the body's major blood-forming organ during the foetal stage. In the liver, the blood stem cells produce the more mature blood cells that form our blood system. At the same time, T- and B-cells are formed, which comprise the basis of our advanced immune system. From birth, this process takes place in the bone marrow and the liver ceases to form blood cells.

Researchers have long believed that the first cells that lead to the development of our immune system, the immune-competent cells, are formed from blood stem cells in the liver while the foetus is developing. Blood stem cells can be found in the liver from day 11󈝸 in a mouse foetus, which is the equivalent of around 6 weeks' gestation in humans.

In the current study, which was performed on mice, researchers showed that these cells linked to our immune system are formed even earlier than this, in the embryo's yolk sac, i.e. before the first blood stem cells are formed. In the human embryo, the yolk sac is one of the three foetal sacs and appears in around the fifth week of pregnancy.

"The question we have posed is whether the immune system is formed in a different way in the foetus than in an adult and how early in the development of the foetus the cells that form our early immune system can be found. Knowledge of this is important because it helps us to understand how and when our immune system begins to form and what can go wrong in that process", explained Charlotta Böiers, a postdoctoral fellow at Lund University.

Childhood leukaemia is one example of how important it is to understand how the immune system is formed. The first mutation on the path to childhood leukaemia has been shown to take place while the child is still in the womb.

"It is still not known in which cell or cells this first step takes place and it is therefore important for us to continue our research on how the immune system starts in humans. The aim is now to continue our investigations in humans", said Charlotta Böiers. If it is possible to prove that the cells mutate at this very early stage of development, then this would increase our understanding of how childhood leukaemia occurs.

"These first cells seem to disappear in the late stages of development of the foetus. This may not happen when there is a mutation. Perhaps the defective cells instead remain alive, and further mutations occur that in turn could lead a child to develop cancer."
-end-
Publication:

'Lymphomyeloid Contribution of an Immune-Restricted Progenitor Emerging Prior to Definitive Hematopoietic Stem Cells', Cell Stem Cell The study is a collaboration between the University of Oxford and Lund University. The senior author of the article is Sten-Eirik Jacobsen from the University of Oxford and the first author is postdoctoral fellow Charlotta Böiers from Lund University.

Lund University

Related Immune System Articles from Brightsurf:

How the immune system remembers viruses
For a person to acquire immunity to a disease, T cells must develop into memory cells after contact with the pathogen.

How does the immune system develop in the first days of life?
Researchers highlight the anti-inflammatory response taking place after birth and designed to shield the newborn from infection.

Memory training for the immune system
The immune system will memorize the pathogen after an infection and can therefore react promptly after reinfection with the same pathogen.

Immune system may have another job -- combatting depression
An inflammatory autoimmune response within the central nervous system similar to one linked to neurodegenerative diseases such as multiple sclerosis (MS) has also been found in the spinal fluid of healthy people, according to a new Yale-led study comparing immune system cells in the spinal fluid of MS patients and healthy subjects.

COVID-19: Immune system derails
Contrary to what has been generally assumed so far, a severe course of COVID-19 does not solely result in a strong immune reaction - rather, the immune response is caught in a continuous loop of activation and inhibition.

Immune cell steroids help tumours suppress the immune system, offering new drug targets
Tumours found to evade the immune system by telling immune cells to produce immunosuppressive steroids.

Immune system -- Knocked off balance
Instead of protecting us, the immune system can sometimes go awry, as in the case of autoimmune diseases and allergies.

Too much salt weakens the immune system
A high-salt diet is not only bad for one's blood pressure, but also for the immune system.

Parkinson's and the immune system
Mutations in the Parkin gene are a common cause of hereditary forms of Parkinson's disease.

How an immune system regulator shifts the balance of immune cells
Researchers have provided new insight on the role of cyclic AMP (cAMP) in regulating the immune response.

Read More: Immune System News and Immune System Current Events
Brightsurf.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.