What does self antigen refer to in the immune response?

Self antigens refer to molecules, often proteins, that are present on the surface of an individual's own cells. These antigens are recognized by the immune system as belonging to the body, indicating that the cells are part of the organism. This recognition is crucial for the proper functioning of the immune response, as it allows the immune system to distinguish between the body's own cells and foreign invaders, such as pathogens.

In a healthy immune system, self antigens help to prevent an immune response against the body's own tissues, which is vital for maintaining immune tolerance. When self antigens are properly recognized, it helps in avoiding autoimmune reactions where the immune system mistakenly attacks the body’s own cells.