Challenges and promise for the development of human immune monitoring.

The immune system is critical for protection and health maintenance and is likely required for a long lifespan. Yet, despite its importance for health, the ability to assess its quality of function has been poor, nor is much known on its variation between individuals. Hence direct assessment of immune health has largely been missing from medicine, and metrics of immune health are not well defined, especially in non-extreme states. This is chiefly due to the high complexity of the immune system. Recently emerging technologies now enable broad surveying of many immune system components at high resolution, setting forth a transformation of immunology and, through it, medicine. Such technologies enable, for the first time, high-resolution monitoring of an individual's immune system. The resulting information can be used for diagnostic and prognostic purposes, as well as to provide a quantitative, global view of the immune system, i.e. "systems immunology." This is especially relevant in the context of aging, in which the immune system exhibits profound alterations in state and function.