Autoimmunity

The immune system is responsible for the orchestration of immune responses to viruses, bacterias, parasites, and mutagenic cells. In a healthy individual, the immune system won't attack its host ("self"), only what's considered foreign ("non-self"). But some individual's immune systems lose the ability to distinguish self from non-self. In these cases, the immune system starts to attack the "self" and that's what we call an autoimmune response.

But how does this happen?

The mechanisms themselves are yet not fully understood but we know that autoimmunity can occur through autoimmune antibodies or autoimmune T-cells.

B-cells- are produced ate the bone marrow where the antibodies they carry are also set. Before leaving, all are tested for autoreactivity. If they respond to self-components, they die but if they move to the spleen they are tested once again for autoreactivity. If they pass the test, they are sent to the lymph nodes waiting for an infection.

Antibodies- find and neutralize pathogens or mark these pathogens so the immune system can find and remove them.

Killer T-cells- their job is to find foreign peptides in the surface of the cells and attack.

T-cells- are produced in the bone marrow and are tested for autoreactivity in the thymus. An autoreactive t-cell can leave the thymus, but if they recognize self-peptides without signals of inflammation t-cells die.

So how can autoreactive cells be activated?

Well this can happen through 3 different processes.

- molecular mimicry

- bystander activation

- epitope spreading

The development of autoimmune diseases depends on genetics, environmental factors (virus, bacterias, parasites, diet or even drugs)

References

(2015). Clevalab.com. https://www.clevalab.com/post/what-are-autoimmune-diseases

‌All Cartoons – Cell Cartoons. (2023). Cellcartoons.net. https://cellcartoons.net/cartoons-all/

‌CS, A. (2020). Favorite Cell Biology Cartoons – Cell Cartoons. Cellcartoons.net. https://cellcartoons.net/favorite-cartoons/

Autoantibodies and autoimmunity molecular mechanism in health and diseases (1st edition 2005)

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