Beutler and Hoffmann’s work enhanced our understanding of the activation of innate immunity in humans. In other words, the link between cytokine and swelling and related issues. Among other things, this work resulted in the development of Etanercept, a treatment for Psoriasis, rheumatoid arthritis, and Crohn’s disease.
Steinman discovered dendritic cells and the role they play in adaptive immunity. These are part of the mammalian immune system. They mediate between antigens (molecular clues carried by invading or unwanted objects such as bacteria) and other immune system cells. Among other things, this is part of the process that ultimately causes your lymph nodes to swell up.
So the whole Nobel Thing this year as all about swelling up!