Aantigeeniä

Aantigeeniä, also known as antigen, is a substance that triggers an immune response within the body. Antigens are typically foreign substances that are not recognized as belonging to the self. This recognition is crucial for the immune system's ability to identify and eliminate threats.

The immune system encounters antigens on the surface of pathogens like bacteria, viruses, fungi, and parasites. It can also be triggered by substances from transplanted organs or tissues, and even by abnormal cells, such as cancer cells. In some cases, the immune system can also mistakenly identify harmless substances, like pollen or certain foods, as antigens, leading to allergic reactions.

When the immune system detects an antigen, it mobilizes various cells and molecules to neutralize or eliminate it. This process involves the production of antibodies, which are proteins that specifically bind to antigens, marking them for destruction by other immune cells. The immune system also develops a memory for specific antigens, allowing for a faster and stronger response upon subsequent exposures. Understanding antigens is fundamental to immunology, vaccinology, and the study of infectious diseases and autoimmune disorders.