After infection with viruses, parasites and bacteria the protein SerpinB2 becomes very abundant in macrophages, which are white blood cells involved in inflammation. Unfortunately, what this protein is doing is very unclear. We have found that macrophage SerpinB2 dampens the responses of other immune cells. This grant aims to determine how this is achieved and thereby help resolve the role of this protein in a number of diseases such as cancer, lupus, asthma and pre-eclampsia.