What are B cells, and why do they matter in type 1 diabetes? New study highlights the importance of immune cell type

At a glance …

• Specific immune cells are responsible for the autoimmune attack which takes place in T1D (B cells). There are also cells which try and protect you by trying to stop this attack, called Tregs. In T1D, B cells can influence the immune system to mistakenly attack your body’s insulin-producing cells 

• Researchers looked at the quantities of different immune cells to see if they would influence the success of an islet transplant. They found that if B cell levels are decreased, the transplant had a higher success rate. They also found that in mice with fewer B cells, there was less destruction of insulin-producing cells  

• If doctors can reduce B cell levels with targeted therapies, T1D could develop more slowly, allowing Tregs to prevent attack on insulin-producing cells 

What do the results of the study show?

A new study, published in Diabetes, co-funded by Breakthrough T1D, has strongly suggested that B cells are responsible for the reduced levels of Tregs seen in people with in T1D.  

The researchers experimented with different levels of B cells in mice with T1D, transplanting insulin-producing cell clusters (islets) into them. When the level of B cells were reduced  in the transplants, there was an increase in transplant success. The Tregs were able to support the islets and offered them protection from immune destruction. Whe looking at the diabetic mice, the research team found that Tregs were markedly absent when compared to an increased number of B cells. 

Finally, the team looked at mice with fewer B cells and noticed that there was less destruction of insulin-producing cells when compared to mice with a ‘sufficient’ amount. 

These findings all suggest that B cells are the culprits for the destruction of the protective Tregs. It also suggests that therapies which protect Tregs could be beneficial in slowing T1D development. If these treatments were combined with methods to target B cells, islet transplants could be more successful.  

Why does this matter for people with T1D?

T1D is an autoimmune condition, meaning that the body’s own immune system mistakenly attacks itself, instead of harmful attackers such as viruses or bacteria.  

B cells and Tregs are heavily involved in the development of T1D. B cells are thought to drive the attack on the insulin-producing cells, while Tregs are decreased during this process, meaning their ability to protect the body is reduced. 

Rachel Connor, Director of Research Partnerships, said,

“Research into the root causes of T1D is paramount in understanding how to prevent people from developing the condition in the future. Studying the immune system at the cellular level allows us to understand what happens in the earliest stages of T1D. With this research, our understanding of the T1D autoimmune attack is strengthened. This can not only guide work to design treatments to prevent T1D but also teach us how to protect new insulin producing cells that could be transplanted into people with existing T1D.”

What is the immune system?

The immune system is made up of a complex network of many different types of cells. These include cells which remove infection, cells which respond to allergens and cells which produce antibodies. Antibodies are proteins which recognise foreign bodies such as bacteria or viruses, and signal for the immune system to destroy them. They also have a ‘memory’, meaning when you have antibodies against one foreign body, your body will remember it in the future.  

What are B cells and T cells?

B cells

B cells are part of the immune system and are responsible for producing antibodies and memory cells. These work together to remember infections and protect you from them in the future. They exist throughout your body, including in the blood and in the pancreas.  

T cells

There are a wide variety of T cells. There are cells which activate the B cells when an immune response is required, cells which kill infected cells, and cells which provide long lasting immunity.  

T cells also have a sub-population known as T-regulatory cells (Tregs). These cells work to stop the body attacking itself (autoimmunity). You could say they are the brakes; they slow down and stop any time your body mistakes your own cells as foreign.  

Are Breakthrough T1D funding any of this research?

The study in question was co-funded by Breakthrough T1D, alongside many other projects investigating how we can target B cells and protect Tregs. This would slow down the autoimmune attack in T1D. These include:  

• Joanne Boldison: Joanne was looking at B cells and how we can target them in the pancreas to protect the insulin producing cells. The data generated allowed her to apply to the Helmsley Charitable Trust and to be awarded a further research grant  

•  James Pearson: James’ project is researching if time of day affects the immune system’s ability to regulate itself