New cell behaviour discovered in the immune system which affects rheumatoid arthritis

March 2021: Scientists at the Centre for Inflammation Research have discovered a previously unknown behaviour of key cells in the immune system which affects the course of common autoimmune conditions.

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Hand cross-section showing inflamed knuckle joint seen in rheumatoid arthritis.
Cells called neutrophils contribute to joint inflammation seen in auto-immune conditions like rheumatoid arthritis.

These cells, called neutrophils, are known to encourage inflammation in joint fluid. Long-term inflammation can lead to tissue damage seen in auto-immune diseases like rheumatoid arthritis. However, new research shows that neutrophils have another role in helping to calm inflammation, making their behaviour more complex than thought before.

Neutrophils are attracted to the joint fluid by clusters of biological tags called antibodies that can stick to joint tissue, encouraging inflammation and sending signals for other neutrophils to arrive. This creates a snowball effect that leads to damaging chronic joint inflammation, only resolved when other immune cells clear away the neutrophils.

Emerging evidence demonstrates that the antibody clusters trigger their own uptake by neutrophils. The neutrophils then commit programmed suicide, sending out ‘find me’ and ‘eat me’ signals to cells which clear them away and encourage tissue healing.

Knowledge of this complex cell behaviour should be useful in the development of treatments for diseases like rheumatoid arthritis.

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