What role do antigens play in the immune system?

Antigens play a crucial role in the immune system primarily by interacting with immune system cells. When the immune system detects a foreign substance, such as a pathogen or any other potentially harmful entity, the antigens on their surface are recognized by various immune cells, including lymphocytes (T cells and B cells). This recognition is essential for initiating an immune response.

For instance, T cells can directly bind to antigens presented by other cells, which helps in identifying and attacking infected cells. B cells, on the other hand, recognize antigens directly, leading to the production of antibodies that target those specific antigens for neutralization or destruction. This interaction is vital for the development of adaptive immunity, enabling the body to remember and respond more efficiently to re-infections by the same pathogen in the future.

In summary, antigens serve as key signals that engage the different components of the immune system, facilitating the recognition and response to pathogens.