What is meant by immune tolerance?

Immune tolerance refers to the mechanism by which the immune system learns to recognize and accept the body's own tissues as "self." This is crucial in preventing the immune system from launching an attack against the body's own cells, which could lead to autoimmune diseases. In healthy individuals, immune tolerance helps maintain a balance between responding to harmful pathogens while not reacting to the body’s own proteins and cells. This ability is developed through various processes during immune system training, particularly during T cell development in the thymus and through interactions with other immune cells.

The other options address different concepts related to immune system function. The idea of a strong immune response pertains to the system's ability to fight off infections, but that does not define tolerance. The notion of impaired immune function describes conditions such as immunodeficiency, which is distinct from tolerance. Lastly, the development of new immune cells is a part of the immune response to infection, rather than a reflection of tolerance.