I am a type 1 Diabetic. Why did my immune system target and specifically kill just the insulin secreting cells of my pancreas? Why not target other organs too?
In: Biology
They are cells that dump multiple types of hormones directly into the blood. Making them a clear target for a mixed up immune system. It’s why autoimmune thyroid diseases are also pretty common. Making chemicals makes a bullseye for the immune system to decide ‘get this guy”
Regrettable the answer to your question is that we don’t know. Your question sort of implies that there is some purpose in only attacking one type of tissues.
There are of course autoimmune diseases that target more than one type of tissues within the body.
Which is a long way of saying. No one knows.
Type 1 diabetes is just one of many types of autoimmune diseases, and each disease depends on which type (or types) of cell(s) the body’s immune system decided was the enemy.
Some recent research points to hybrid insulin peptides (HIPs) being a culprit in at least some forms of type 1 diabetes. Basically insulin fragments (after an enzyme has cut up insulin into smaller pieces) make a peptide bond to other peptides. These HIPs have some features that are still insulin-like, but the T-cell recognize HIPs as foreign bodies and become triggered to think that insulin is a product of a foreign cell. Since Beta cells produce insulin and insulin is considered foreign, then beta cells must be the enemy and the immune system attacks them.
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The way our body makes T-cells and antibodies (B-cells) is incredible. There are genes that code for receptors, that mutate in very controlled ways to create billions of different receptors that can recognize basically any foreign substance. When a single cell with the right receptor finds it’s match, it rapidly multiplies and attacks it.
The problem is, these mutations are random and end up making receptors that recognize stuff inside the body! Your immune system also has ways of filtering those out – autoimmune disease is when *this process* doesn’t work correctly.
You have B-cells and T-cells that recognize your insulin secreting cells as their target and all the regulatory mechanisms have failed to stop them. Modern treatments like Teplizumab work to slow down the activity of your immune system, some work to speed up the regulatory systems that suppress these reactions. The sci-fi future is being able to kill off those self-reactive cells – which yes we’re working on.
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