The immune system is the body’s tool for preventing or limiting infection. Its complex network of cells, organs, proteins, and tissues enables the immune system to defend the body from pathogens.
A fully functional immune system can distinguish healthy tissue from unwanted substances. If it detects an unwanted substance, it will mount an immune response — a complex attack to protect the body from invaders like bacteria, viruses, fungi, and parasites. It also recognizes and removes dead and faulty cells.
In autoimmune diseases and allergies, the immune system mistakenly perceives healthy tissue as unhealthy and launches an unnecessary attack, leading to uncomfortable and sometimes dangerous symptoms.
This article will look at some of the main features of the immune system and how it defends the body from pathogens and other invaders. It will also look at problems that can arise with the immune system.