body's defense mechanism against harmful pathogens and foreign substances
The immune response, also known as the immunological response, is the body's defense mechanism against harmful pathogens like bacteria, viruses, and other foreign substances. It involves the activation of immune cells, such as white blood cells, which identify, attack, and eliminate these invaders to protect the body from infections and diseases. This process can also mistakenly target the body's own cells, leading to autoimmune conditions like alopecia areata, where the immune system attacks hair follicles, causing hair loss.