Abstract
The immune system is a complex biological system that is responsible for the detection and elimination of foreign invaders, including viruses, bacteria and even tumor cells. A successful immune response involves a coordinated and highly regulated response among numerous cell types and molecules in the body. In general, most immune responses are successful, and lead to elimination of the foreign invader with minimal collateral damage to the host. However, in rare cases, immune responses can fail, resulting in host damage or death. Failure can arise either because the response is insufficient, and the invader thus replicates unchecked, or because the response is overly exuberant, resulting in immune-mediated damage to the host. Successful immune responses require an optimal trade off between these two extremes. For the most part, the last century of immunology has been a highly reductionist attempt to catalog the cells of the immune system, and the molecules that regulate their function. This endeavor has been highly successful, but a systems level quantitative understanding of how all the parts of the immune system function together remains a significant challenge. In my talk I will focus on the principles governing immune activation, and will provide a specific example of a strategy the immune system might use to balance the need to respond against invaders against the risks of an overexuberant response.