The immune system can sometimes cause problems in our bodies, especially in autoimmune diseases. Here are some ways this happens:

1. Autoantibody Production:

   • In diseases like systemic lupus erythematosus (SLE), about 90% of people make autoantibodies. These can harm healthy tissue.

2. Cell-Mediated Immunity:

   • T cells are a type of immune cell that can attack healthy tissues. CD4+ T cells are often responsible for causing inflammation. For instance, in rheumatoid arthritis, these T cells can invade the synovial tissue, which is important for joint health.

3. Cytokine Release:

   • When our bodies produce too many signaling molecules called cytokines (like TNF-α and IL-6), it can lead to ongoing inflammation. This inflammation can damage tissues over time.

4. Complement Activation:

   • Some autoimmune diseases, like glomerulonephritis, show how the complement system (a part of our immune system) can cause harm. In about 20% of these cases, the complement system attacks the kidneys, leading to damage.

In summary, the immune system can cause a lot of harm in autoimmune diseases. This creates a cycle where inflammation leads to more damage, making the disease worse.